--- title: "Lesson 3 — Day Supply Calculations | AlabamaPharmTech.com" description: "Day supply calculations for retail pharmacy: tablets, liquids, inhalers, insulin, and eye drops. Interactive lesson with 40+ practice problems." lang: en json-ld: | { "@context": "https://schema.org", "@type": "LearningResource", "name": "Day Supply Calculations", "description": "Day supply calculations for retail pharmacy: tablets, liquids, inhalers, insulin, and eye drops. Interactive lesson with 40+ practice problems.", "url": "https://www.alabamapharmtech.com/lessons/lesson3-day-supply.html", "inLanguage": "en", "learningResourceType": "Interactive lesson", "educationalLevel": "Beginner", "isPartOf": { "@type": "Course", "name": "Pharmacy Math Mastery", "url": "https://www.alabamapharmtech.com/pharmacy-math-practice" }, "provider": { "@type": "Organization", "name": "AlabamaPharmTech", "url": "https://www.alabamapharmtech.com" } } --- AlabamaPharmTech .com An Allied Health Academy company Pharmacy Math Mastery ALBOP-Approved · PTCB & NHA Prep Overall progress 33% Lessons 1 Math Foundations 25 min · Complete ✓ 2 Dimensional Analysis 30 min · Complete ✓ 3 Day Supply Calculations 40 min · In progress 4 Dosage Conversions 35 min 5 Ratio, Proportion, Percent 30 min 6 Sig Interpretation 30 min Final exam ★ Bringing It All Together Cumulative · All 6 lessons AlabamaPharmTech.com › Pharmacy Math Mastery › Lesson 3 of 6 Core # Lesson 3: Day Supply Calculations Calculate days supply for every drug type you will see in real practice and on the PTCB exam — tablets, liquids, insulin, inhalers, eye drops, and topicals. [Back to Course](/pharmacy-math-practice) [Back to Dashboard](/modules) Overview Examples Practice 44 Quiz Master formula — works for every drug type Days Supply = Total Quantity Dispensed ÷ Amount Used Per Day The only formula you need. The challenge is knowing what counts as "quantity" and "per day" for each drug type. Tablets & Capsules DS = Qty ÷ (dose × freq/day) 90 tabs, 1 tab BID → 90 ÷ 2 = **45 days** Oral Liquids DS = Total mL ÷ mL per day 150 mL, 5 mL BID → 150 ÷ 10 = **15 days** Insulin DS = (pens × units/pen) ÷ units/day 3 pens, 300 u each, 30 u/day → 900 ÷ 30 = **30 days** Inhalers DS = Total puffs ÷ puffs per day 200 puffs, 2 puffs BID → 200 ÷ 4 = **50 days** Eye / Ear Drops DS = (vol × 20 drops/mL) ÷ drops/day 2.5 mL, 1 drop each eye QD → 50 ÷ 2 = **25 days** Topicals & Gels DS = total grams ÷ grams per day 30 g, apply 1 g BID → 30 ÷ 2 = **15 days** Insulin pen sizes — memorize these Standard U-100 pen (most) = **300 units** (3 mL × 100 u/mL) Standard vial = **1,000 units** (10 mL × 100 u/mL) Toujeo SoloStar U-300 = **450 units** (1.5 mL) Tresiba / Humalog U-200 = **600 units** (3 mL × 200 u/mL) Always find **total units first**, then divide by daily dose. Common inhaler puff counts Albuterol HFA (ProAir/Ventolin) = **200 puffs** Flovent HFA 44/110/220 mcg = **120 puffs** Symbicort = **120 puffs** Advair Diskus = **60 doses** (not puffs) Spiriva Respimat = **60 actuations** (2 puffs = 1 dose) PRN inhalers: always use **maximum** frequency for day supply. Eye drop standard 1 drop = approximately **0.05 mL** Therefore: **20 drops per mL** (standard used on PTCB) "Each eye" = **2 drops per dose**, not 1 Latanoprost 2.5 mL = ~50 drops total Always round **down** to whole days. Frequency quick reference QD / QAM / QHS = **1×/day** BID = **2×/day**  |  TID = **3×/day** QID = **4×/day**  |  Q6H = **4×/day** Q8H = **3×/day**  |  Q4H = **6×/day** Q12H = **2×/day**  |  Q4-6H PRN = use **Q4H** (max) **★ PTCB exam strategy:** Day supply appears in the Order Entry & Processing domain (22.5% of exam). Expect 3–5 day supply questions. The exam will give you a sig code and a quantity — your job is to translate the sig into doses per day, then divide. Insulin and inhaler day supply are the most commonly missed because students skip the step of finding total units/puffs first. **The 4 most common mistakes:** 1\. Forgetting to multiply pens × units/pen before dividing insulin — _always find total units first_ 2\. Counting "each eye" as 1 drop instead of 2 3\. Using doses per administration instead of total doses per day 4\. Rounding up instead of down — _always round DOWN for day supply_ Six worked examples — one per drug type. These mirror the style and complexity of real PTCB exam questions. Work through each one yourself before reading the solution. Easy Retail PTCB style Patient at the counter picks up metformin 500 mg. Rx reads: Take 1 tablet by mouth twice daily. Quantity dispensed: 60 tablets. How many days will 60 tablets last at 1 tab BID? Step 1 — Translate BID → doses per day: BID = 2 times per day → 1 tab × 2 = 2 tablets/day Step 2 — Apply the formula: 60 tabs ÷ 2 tabs/day = 30 days ✓ Day supply: 30 days Easy Retail PTCB style Pediatric Rx: amoxicillin 250 mg/5 mL suspension. Sig: 5 mL by mouth twice daily. Quantity: 150 mL bottle. How many days will 150 mL last at 5 mL BID? Step 1 — Daily volume: 5 mL × 2 (BID) = 10 mL/day Step 2 — Day supply: 150 mL ÷ 10 mL/day = 15 days ✓ Day supply: 15 days Medium Retail PTCB style Patient picks up insulin glargine (Lantus) SoloStar pens. Sig: inject 30 units subcutaneously every night at bedtime. Quantity: 1 box of 5 pens (each pen = 300 units). How many days will 1 box of 5 pens last at 30 units nightly? Step 1 — Find total units (critical first step): 5 pens × 300 units/pen = 1,500 units total Step 2 — Day supply: 1,500 units ÷ 30 units/day = 50 days ✓ Day supply: 50 days **The #1 insulin trap:** Dividing 5 (pens) by 30 (units/day) gives 0.17 — obviously wrong. You must calculate total units first. Every insulin day supply problem starts with: pens × units/pen. Medium Retail PTCB style Patient picks up albuterol HFA (ProAir MDI). Sig: inhale 2 puffs every 4–6 hours as needed for shortness of breath. Canister contains 200 puffs. Use maximum PRN frequency for day supply. At max PRN use (Q4H = 6 times/day), what is the day supply for 1 inhaler? Step 1 — Puffs per day at max frequency (Q4H = 6×/day): 2 puffs × 6 = 12 puffs/day Step 2 — Day supply (round down): 200 ÷ 12 = 16.67 → 16 days ✓ Day supply: 16 days — always round down Medium Retail PTCB style Patient picks up latanoprost 0.005% ophthalmic solution. Sig: instill 1 drop in each eye every evening. Bottle size: 2.5 mL. How many days will the 2.5 mL bottle last? Step 1 — Total drops in bottle (20 drops per mL): 2.5 mL × 20 = 50 drops total Step 2 — Drops per day ("each eye" = both eyes = 2 drops): 1 drop × 2 eyes × 1 (QHS) = 2 drops/day Step 3 — Day supply: 50 drops ÷ 2 drops/day = 25 days ✓ Day supply: 25 days **"Each eye" means 2:** Every time you see "each eye" or "both eyes," multiply drops per dose by 2. Entering 1 drop per day instead of 2 doubles the day supply — a common insurance audit flag. Hard Patient scenario PTCB style Mrs. Torres has type 2 diabetes. Rx: insulin lispro (Humalog), inject 10 units with each meal and 5 units with bedtime snack. She eats 3 meals per day. Quantity: 2 vials (1,000 units each). How many days will 2 vials last for Mrs. Torres? Step 1 — Mealtime units per day: 10 units × 3 meals = 30 units Step 2 — Add bedtime dose: 30 + 5 = 35 units/day Step 3 — Total units in 2 vials: 2 × 1,000 = 2,000 units Step 4 — Day supply (round down): 2,000 ÷ 35 = 57.1 → 57 days ✓ Day supply: 57 days Difficulty Easy Medium Hard Context Retail Hospital Patient Easy Retail Tablets Patient picks up metformin 500 mg. Sig: 1 tablet by mouth twice daily. How many days will 60 tablets last? Check answer Show solution **Answer: 30 days** 1 tab × 2 (BID) = 2 tabs/day. 60 ÷ 2 = **30 days**. BID = twice per day. Easy Retail Tablets Patient picks up lisinopril 10 mg. Sig: 1 tablet by mouth once daily. A 90-tablet supply will last how many days? Check answer Show solution **Answer: 90 days** 1 tab × 1 (QD) = 1 tab/day. 90 ÷ 1 = **90 days**. QD = once per day. Easy Retail Tablets 10-day antibiotic course. Sig: 1 capsule by mouth three times daily. How many capsules are needed for a complete 10-day supply? Check answer Show solution **Answer: 30 capsules** 1 cap × 3 (TID) = 3 caps/day. 3 × 10 days = **30 capsules**. Working backwards from days to quantity. Easy Retail Tablets Patient on atorvastatin 20 mg. Sig: 1 tablet by mouth at bedtime. Quantity: 30 tablets. How many days will 30 tablets last at 1 tablet QHS? Check answer Show solution **Answer: 30 days** QHS = every bedtime = once daily = 1 tab/day. 30 ÷ 1 = **30 days**. QHS, QD, and QAM all mean once per day. Med Retail Tablets Prednisone taper pack. Sig: 3 tablets daily for 5 days, then 2 tablets daily for 5 days, then 1 tablet daily for 5 days. How many total tablets are needed for the full taper? Check answer Show solution **Answer: 30 tablets** Phase 1: 3 × 5 = 15 tabs. Phase 2: 2 × 5 = 10 tabs. Phase 3: 1 × 5 = 5 tabs. Total: 15 + 10 + 5 = **30 tablets** over 15 days. Med Retail Tablets Ibuprofen 400 mg. Sig: 2 tablets by mouth every 6 hours as needed for pain. Quantity: 120 tablets. Using maximum scheduled dosing (Q6H = 4 times/day), what is the day supply? Check answer Show solution **Answer: 15 days** 2 tabs × 4 (Q6H = 4×/day) = 8 tabs/day at max. 120 ÷ 8 = **15 days**. PRN medications: always use maximum daily frequency to calculate day supply. Med Retail Tablets Sig: Take ½ tablet daily for 2 weeks, then 1 tablet daily after that. Quantity: 60 tablets. How many days will 60 tablets last following this titration schedule? Check answer Show solution **Answer: 67 days** Phase 1 (2 weeks = 14 days): 0.5 tab/day × 14 = 7 tabs used. Remaining: 60 − 7 = 53 tabs. Phase 2: 53 tabs ÷ 1 tab/day = 53 more days. Total: 14 + 53 = **67 days**. Med Retail Tablets Sig: 1 tablet every morning. Insurance approves a 90-day supply. Quantity: 90 tablets. What day supply should be entered into the system? Check answer Show solution **Answer: 90 days** QAM = every morning = once daily = 1 tab/day. 90 ÷ 1 = **90 days**. Hard Hospital Tablets Discharge Rx. Warfarin dose varies: Monday/Wednesday/Friday take 2 tablets of 2.5 mg; all other days take 1 tablet. Dispensing 2.5 mg tablets. Patient needs a 4-week supply. How many 2.5 mg warfarin tablets are needed for exactly 4 weeks? Check answer Show solution **Answer: 40 tablets** Per week: Mon/Wed/Fri (3 days) × 2 tabs = 6 tabs. Other 4 days × 1 tab = 4 tabs. Total per week = 6 + 4 = **10 tabs**. For 4 weeks: 10 × 4 = **40 tablets**. Hard Patient scenario Tablets Sildenafil 50 mg. Sig: Take 1 tablet as needed approximately 1 hour before activity, no more than once daily. Patient reports using it about 3 times per week. Quantity: 30 tablets. Based on the patient's reported use (3×/week), how many days will 30 tablets last? Check answer Show solution **Answer: 70 days** 3 tablets/week ÷ 7 days/week = 3/7 tablets per day. 30 ÷ (3/7) = 30 × (7/3) = **70 days**. Alternatively: 30 tablets ÷ 3 per week = 10 weeks × 7 = 70 days. Easy Retail Oral liquid Child Rx: amoxicillin 250 mg/5 mL suspension. Sig: 5 mL by mouth twice daily. Quantity: 150 mL. What is the day supply for 150 mL at 5 mL BID? Check answer Show solution **Answer: 15 days** 5 mL × 2 (BID) = 10 mL/day. 150 mL ÷ 10 mL/day = **15 days**. Easy Retail Oral liquid Allergy syrup. Sig: 10 mL by mouth once daily at bedtime. Quantity: 120 mL bottle. How many days will the 120 mL bottle last? Check answer Show solution **Answer: 12 days** 10 mL × 1 (QHS) = 10 mL/day. 120 mL ÷ 10 mL/day = **12 days**. Easy Patient scenario Oral liquid Azithromycin Z-pack suspension for a child. Sig: 10 mL on Day 1, then 5 mL once daily on Days 2–5. How many total mL are needed for the complete 5-day course? Check answer Show solution **Answer: 30 mL** Day 1: 10 mL. Days 2–5: 5 mL × 4 days = 20 mL. Total: 10 + 20 = **30 mL**. A standard azithromycin 200 mg/5 mL pack is exactly 30 mL for this reason. Med Retail Oral liquid Prednisolone oral solution. Patient weighs 22 kg. Prescribed dose: 1 mg/kg/day. Concentration available: 15 mg/5 mL. How many mL should the patient receive per day? Check answer Show solution **Answer: 7.3 mL** Dose: 1 mg/kg × 22 kg = 22 mg/day. Volume: 22 mg ÷ (15 mg/5 mL) = 22 × (5/15) = **7.3 mL/day**. Round to nearest tenth. Med Retail Oral liquid Augmentin ES suspension. Sig: 6.4 mL by mouth twice daily for 10 days. What total volume (mL) is needed for the complete 10-day course? Check answer Show solution **Answer: 128 mL** 6.4 mL × 2 (BID) = 12.8 mL/day. 12.8 mL × 10 days = **128 mL**. Pharmacies typically dispense a 150 mL bottle, but the day supply calculation is based on the prescribed dose. Med Patient scenario Oral liquid Ms. Carter takes hydroxyzine syrup for anxiety. Sig: 5 mL three times daily as needed. She reports taking it once daily on average. Quantity: 1 pint (473 mL). The question asks what to enter based on reported use. Based on her reported use of 5 mL once daily, what day supply should be entered? Check answer Show solution **Answer: 94 days** At reported use of 5 mL × 1 daily = 5 mL/day. 473 mL ÷ 5 mL/day = 94.6 → **94 days** (round down). Real-world note: if entering for insurance, most systems use max PRN dose (15 mL/day → 31 days). This question specifies reported use, so 94 days is correct here. Hard Hospital Oral liquid Post-op patient. Lactulose for hepatic encephalopathy. Dose: 30 mL three times daily. Patient receives one 2 L (2,000 mL) bottle. How many days will the 2 L bottle last at 30 mL TID? Check answer Show solution **Answer: 22 days** 30 mL × 3 (TID) = 90 mL/day. 2,000 mL ÷ 90 mL/day = 22.2 → **22 days** (round down). Hard Patient scenario Oral liquid OTP clinic patient. Methadone 5 mg/5 mL. Daily observed dose: 80 mg. Patient receives 6 take-home bottles of 100 mL each. How many days of take-home supply do 6 × 100 mL bottles provide at 80 mg/day? Check answer Show solution **Answer: 7 days** Volume per day: 80 mg ÷ (5 mg/5 mL) = 80 mg × (5 mL/5 mg) = 80 mL/day. Total volume: 6 × 100 = 600 mL. 600 ÷ 80 = 7.5 → **7 days** (round down). Easy Retail Insulin Sig: inject 20 units subcutaneously once daily at bedtime. Quantity: 1 SoloStar pen (300 units). How many days will 1 pen last at 20 units/day? Check answer Show solution **Answer: 15 days** 300 units ÷ 20 units/day = **15 days**. Standard SoloStar pen = 300 units (3 mL × 100 u/mL). Easy Retail Insulin Sig: inject 30 units subcutaneously every night. Quantity: 1 box of 5 SoloStar pens (300 units each). How many days will 1 box (5 pens) last at 30 units/day? Check answer Show solution **Answer: 50 days** Total units: 5 × 300 = 1,500 units. 1,500 ÷ 30 units/day = **50 days**. Easy Retail Insulin Humulin R 100 u/mL, 10 mL vial. Sig: inject 15 units before each meal (3 meals per day). A patient injects 15 units before each of 3 daily meals. How many days will one 10 mL vial of Humulin R (100 u/mL) last? Check answer Show solution **Answer: 22 days** Total units: 10 mL × 100 u/mL = 1,000 units. Daily: 15 × 3 = 45 units/day. 1,000 ÷ 45 = 22.2 → **22 days** (round down). Med Retail Insulin Levemir FlexPen (300 units). Sig: inject 40 units twice daily. How many days will one Levemir FlexPen last? Round down. Check answer Show solution **Answer: 3 days** Daily dose: 40 × 2 = 80 units/day. 300 ÷ 80 = 3.75 → **3 days** (round down). Patients on high doses need multiple pens per fill. Med Retail Insulin Sig: inject 12 units with each meal (3 meals/day) + 8 units at bedtime. Quantity: 2 vials (1,000 units each). How many days will 2 vials (2,000 units) last? Round down. Check answer Show solution **Answer: 45 days** Daily: (12 × 3) + 8 = 36 + 8 = 44 units/day. Total: 2,000 units. 2,000 ÷ 44 = 45.4 → **45 days**. Med Patient scenario Insulin Mr. Patel uses 1 unit per 15g carbohydrate. He eats ~60g carbs per meal, 3 meals/day, plus 25 units of basal insulin nightly. Quantity: 3 NovoLog pens (300 units each). How many days will 3 NovoLog pens (900 units) last? Check answer Show solution **Answer: 24 days** Mealtime: (60 ÷ 15) = 4 units/meal × 3 = 12 units/day. Basal: 25 units/day. Total: 12 + 25 = 37 units/day. 900 ÷ 37 = 24.3 → **24 days**. Med Retail Insulin Humulin N 100 u/mL, 10 mL vial. Sig: 30 units every morning and 20 units every bedtime. Patient takes 30 units AM and 20 units PM of Humulin N. How many days will one 10 mL vial provide? Check answer Show solution **Answer: 20 days** Daily: 30 (AM) + 20 (PM) = 50 units/day. Vial = 1,000 units. 1,000 ÷ 50 = **20 days**. Hard Hospital Insulin Toujeo SoloStar pen contains 300 u/mL in a 1.5 mL pen = 450 units per pen. Patient dose: 60 units nightly. Insurance approves 3 pens per fill. How many days will 3 Toujeo pens last at 60 units/day? Round down. Check answer Show solution **Answer: 22 days** Total units: 3 × 450 = 1,350 units. 1,350 ÷ 60 = 22.5 → **22 days**. Important: Toujeo pens = 450 units, not the standard 300 units. This is a common exam trap. Hard Patient scenario Insulin U-200 KwikPen: 200 u/mL × 3 mL = 600 units per pen. Sig: 50 units before each meal, 3 meals per day. How many days will 2 U-200 KwikPens (1,200 units total) last? Round down. Check answer Show solution **Answer: 8 days** Total units: 2 × 600 = 1,200 units. Daily: 50 × 3 = 150 units/day. 1,200 ÷ 150 = **8 days**. U-200 pens hold double the units of standard U-100 pens. Hard Retail Insulin Tresiba U-200 FlexTouch: 200 u/mL × 3 mL = 600 units per pen. Patient dose: 80 units nightly. Quantity: 3 pens. How many days will 3 Tresiba pens (1,800 units) last at 80 units/day? Round down. Check answer Show solution **Answer: 22 days** Total units: 3 × 600 = 1,800 units. 1,800 ÷ 80 = 22.5 → **22 days**. Tresiba U-200 = 600 units/pen. Know your insulin pen sizes cold. Easy Retail Inhaler Sig: inhale 2 puffs every 4–6 hours as needed for wheezing. 1 canister = 200 puffs. Use maximum PRN frequency for day supply. At Q4H (max frequency = 6 times/day), what is the day supply? Check answer Show solution **Answer: 16 days** Max puffs/day: 2 × 6 = 12 puffs/day. 200 ÷ 12 = 16.67 → **16 days**. Always round down. Always use max frequency for PRN inhalers. Easy Retail Inhaler Flovent HFA 44 mcg, 120 actuations. Sig: inhale 2 puffs twice daily. What is the day supply for 1 Flovent inhaler? Check answer Show solution **Answer: 30 days** 2 puffs × 2 (BID) = 4 puffs/day. 120 ÷ 4 = **30 days**. Easy Retail Inhaler Spiriva Respimat 2.5 mcg. Each dose = 2 puffs. Device has 60 actuations. Sig: inhale 2 puffs (= 1 dose) once daily. What is the day supply for the Spiriva Respimat? Check answer Show solution **Answer: 30 days** 2 puffs × 1 (QD) = 2 puffs/day. 60 ÷ 2 = **30 days**. Spiriva Respimat: 60 actuations = 30 doses. Med Retail Inhaler Symbicort 160/4.5 mcg, 120 puffs per inhaler. Sig: inhale 2 puffs twice daily. Patient picks up 3 inhalers. What is the total day supply for all 3 inhalers? Check answer Show solution **Answer: 90 days** Per inhaler: 2 × 2 (BID) = 4 puffs/day. 120 ÷ 4 = 30 days per inhaler. 3 inhalers × 30 = **90 days**. Med Retail Inhaler Advair Diskus 250/50, 60 doses. Sig: inhale 1 dose (blister) twice daily. Note: each blister = 1 dose, not counted in puffs. What is the day supply for Advair Diskus at 1 dose BID? Check answer Show solution **Answer: 30 days** 1 dose × 2 (BID) = 2 doses/day. 60 doses ÷ 2 = **30 days**. Advair Diskus counts doses (blisters), not individual puffs. Med Patient scenario Inhaler COPD patient. Combivent Respimat, 120 actuations. Sig: inhale 1 puff four times daily. How many days will 120 actuations last at 1 puff QID? Check answer Show solution **Answer: 30 days** 1 puff × 4 (QID) = 4 puffs/day. 120 ÷ 4 = **30 days**. QID = four times per day. Hard Hospital Inhaler Perforomist 20 mcg/2 mL nebulizer solution. Box of 60 unit-dose vials. Sig: inhale contents of 1 vial via nebulizer twice daily. How many days will one box of 60 vials last? Check answer Show solution **Answer: 30 days** 1 vial × 2 (BID) = 2 vials/day. 60 ÷ 2 = **30 days**. Nebulizer solutions count by unit-dose vials. Hard Patient scenario Inhaler Patient fills both: Albuterol (200 puffs, 2 puffs Q4–6H PRN) and Flovent 110 mcg (120 puffs, 2 puffs BID). Both filled same day. Which inhaler has the longer day supply? (Use Q4H max for albuterol.) Check answer Show solution **Answer: Flovent — 30 days vs 16 days for albuterol** Albuterol at max Q4H: 2 × 6 = 12/day → 200 ÷ 12 = 16 days. Flovent: 2 × 2 = 4/day → 120 ÷ 4 = 30 days. **Flovent lasts longer at 30 days**. This explains why rescue and controller inhalers get out of sync. Med Retail Eye/ear drops Sig: instill 1 drop in each eye every evening. Bottle: 2.5 mL. Standard: 20 drops per mL. How many days will the 2.5 mL bottle last? Check answer Show solution **Answer: 25 days** Total drops: 2.5 × 20 = 50 drops. Drops/day: 1 × 2 eyes = 2 drops/day. 50 ÷ 2 = **25 days**. Med Retail Eye/ear drops Sig: instill 1 drop in the LEFT eye only, twice daily. Bottle: 5 mL. How many days will the 5 mL bottle last? Check answer Show solution **Answer: 50 days** Total drops: 5 × 20 = 100 drops. Left eye only: 1 drop × 2 (BID) = 2 drops/day. 100 ÷ 2 = **50 days**. Key: only the left eye — not both. Hard Retail Eye/ear drops Post-operative. Sig: instill 1–2 drops in right eye every 4–6 hours. Use 2 drops at maximum frequency (Q4H) for day supply. How many days will 5 mL last using 2 drops 6 times/day in one eye? Round down. Check answer Show solution **Answer: 8 days** Total drops: 5 × 20 = 100 drops. Max use: 2 drops × 6 = 12 drops/day. 100 ÷ 12 = 8.3 → **8 days**. Hard Hospital Eye/ear drops Sig: instill 4 drops in the affected ear 3 times daily for 7 days. Bottle: 10 mL. How many mL are used for the full 7-day course? Does 1 bottle (10 mL) cover the full course? A. 4.2 mL used — 1 bottle is more than enoughB. 8.4 mL used — 1 bottle is more than enoughC. 10 mL used — exactly 1 bottleD. 12 mL used — need 2 bottles Show solution **Answer: 4.2 mL used — 1 bottle is more than enough** Drops/day: 4 × 3 = 12 drops/day. Over 7 days: 12 × 7 = 84 drops. Volume: 84 ÷ 20 drops/mL = **4.2 mL**. One 10 mL bottle is more than enough. Enter 7 days. Easy Retail Topical Sig: apply a thin layer to the affected area twice daily. Estimated use: 0.5 g per application. Quantity: 30 g tube. How many days will the 30 g tube last? Check answer Show solution **Answer: 30 days** 0.5 g × 2 (BID) = 1 g/day. 30 g ÷ 1 g/day = **30 days**. Med Retail Topical Sig: insert 5 g intravaginally once daily at bedtime for 5 days. Tube: 70 g. What day supply should be entered for the 70 g tube at 5 g/day? Check answer Show solution **Answer: 14 days** 5 g × 1 (QHS) = 5 g/day. 70 g ÷ 5 g/day = 14. Enter **14 days** as the calculated day supply, even though the course is only 5 days. Pharmacies enter day supply based on quantity dispensed ÷ daily use. Med Patient scenario Topical Androgel 1%. Sig: apply contents of 2 packets topically once daily. Each packet = 5 g. Box contains 30 packets. A box of 30 packets will last how many days? Check answer Show solution **Answer: 15 days** 2 packets × 1 (QD) = 2 packets/day. 30 ÷ 2 = **15 days**. Count packets per day, not grams, when packets are the dispensed unit. Hard Hospital Topical Atopic dermatitis. Sig: apply thin layer to trunk and arms twice daily. Estimated use: 2 g per application. Quantity: 60 g. How many days will 60 g last at 2 g per application, BID? Check answer Show solution **Answer: 15 days** 2 g × 2 (BID) = 4 g/day. 60 g ÷ 4 g/day = **15 days**. Med Retail Multi-step Patient drops off 3 Rxs: (1) Lisinopril 10 mg #90, 1 QD. (2) Metformin 500 mg #180, 1 BID. (3) Atorvastatin 40 mg #90, 1 QD. Which Rx will run out first? A. Lisinopril — runs out in 90 daysB. Metformin — runs out in 90 daysC. Atorvastatin — runs out in 90 daysD. All three run out at the same time Show solution **Answer: All three run out at the same time** Lisinopril: 90 ÷ 1 = 90 days. Metformin: 180 ÷ 2 = 90 days. Atorvastatin: 90 ÷ 1 = 90 days. **All three are 90-day supplies**. This is a medication synchronization (med sync) fill — aligned intentionally. Med Retail Multi-step Patient fills 30 sertraline tablets (1 QD = 30-day supply) on Day 1. She calls on Day 25 requesting a refill. The pharmacy policy allows refill once 75% of the supply is used. On Day 25, can the patient refill her sertraline? A. No — must wait until Day 30B. No — must wait until Day 27C. No — must wait until Day 23D. Yes — 75% threshold was reached before Day 25 Show solution **Answer: Yes — 75% threshold was reached before Day 25** 75% of 30 days = 22.5 days. Rounded up: earliest refill is **Day 23**. She is calling on Day 25, which is after Day 23. **Yes, she can refill**. By Day 25 she has used 25 out of 30 doses (83%), which exceeds the 75% threshold. Med Patient scenario Multi-step Rx: Adderall XR 20 mg, 2 capsules daily. Qty: 60 capsules. Schedule II — most states limit to 30-day supply. How many days does Qty #60 represent, and is it within the CII limit? A. 30 days — yes, within the 30-day limitB. 30 days — no, exceeds the CII limitC. 60 days — requires special authorizationD. 15 days — must dispense more Show solution **Answer: 30 days — yes, within the 30-day limit** 60 caps ÷ 2 caps/day = **30 days exactly**. This is within the typical CII 30-day limit. If the Rx were for #90 (45 days), it would require clarification or a new Rx. Hard Hospital Multi-step DVT prophylaxis post-discharge. Sig: inject 40 mg subcutaneously once daily. Patient needs 10 days of outpatient therapy. Syringes come in cartons of 10. How many cartons (10 syringes each) are needed for 10 days? A. 1 carton — exactly enoughB. 2 cartons — need 20 syringesC. 1 carton — with extras left overD. 3 cartons — standard dispensing Show solution **Answer: 1 carton — exactly enough** 1 syringe/day × 10 days = 10 syringes. 1 carton = 10 syringes. **Exactly 1 carton**. Know standard carton sizes for common injectables. Hard Retail Multi-step Type 2 diabetes patient. Rx 1: Metformin 1000 mg #180 tabs, 1 BID. Rx 2: Insulin glargine 10 units nightly, 5 pens (300 units each). Which medication runs out first and when? A. Metformin at 90 days — runs out firstB. Insulin at 150 days — runs out firstC. Both run out at 90 daysD. Metformin at 60 days — runs out first Show solution **Answer: Metformin at 90 days — runs out first** Metformin: 180 ÷ (1×2) = 90 days. Insulin: 5 × 300 = 1,500 units ÷ 10 units/day = 150 days. **Metformin runs out first at 90 days**. The patient needs to refill metformin before insulin. Hard Retail Multi-step Insurance requires exactly a 90-day supply. Patient uses 50 units of insulin glargine nightly. SoloStar pens are 300 units each. How many pens are needed to cover exactly 90 days? (Round up — patient must not run short.) Check answer Show solution **Answer: 15 pens** Units needed: 50 × 90 = 4,500 units. Pens: 4,500 ÷ 300 = **15 pens exactly**. When calculating pens to dispense, round up if not a whole number so the patient has enough. Here it divides evenly. Hard Retail Multi-step Vivitrol 380 mg IM injection. Given once every 4 weeks. Patient picks up 1 injection kit. What day supply should be entered for 1 Vivitrol injection? Check answer Show solution **Answer: 28 days** Once every 4 weeks = every 28 days. Enter **28 days**, not 30. The manufacturer specifies 4 weeks (4 × 7 = 28), not every calendar month. Hard Hospital Multi-step Home infusion: vancomycin 1,500 mg in 250 mL NS, infuse once daily. Specialty pharmacy dispenses 7 bags. What day supply should be entered for these 7 vancomycin IV bags? Check answer Show solution **Answer: 7 days** 1 bag per day × 7 bags = **7 days**. IV bags for home infusion are entered as 1 day per bag when the sig is once daily. Hard Patient scenario Multi-step Oxycodone 5 mg. Sig: take 1–2 tablets every 4–6 hours as needed for pain. Qty: 60 tablets. For CII, use maximum dosing for day supply. What day supply should be entered using maximum dosing (2 tabs Q4H)? Check answer Show solution **Answer: 5 days** Maximum: 2 tabs × 6 (Q4H) = 12 tabs/day. 60 ÷ 12 = **5 days**. CII controlled substances use maximum dosing for day supply entry. This flags appropriately in PMP systems. Hard Retail Multi-step Medrol Dosepak (methylprednisolone 4 mg). Fixed taper: Day 1: 6 tabs, Day 2: 5 tabs, Day 3: 4 tabs, Day 4: 3 tabs, Day 5: 2 tabs, Day 6: 1 tab. How many total tablets are in the Medrol Dosepak, and what is the day supply? Check answer Show solution **Answer: 21 tablets — 6 days** 6+5+4+3+2+1 = **21 tablets**, taken over **6 days**. The Medrol Dosepak is a pre-packaged fixed taper. Memorize: 21 tablets, 6 days. Very common retail dispensing scenario. **How this quiz works:** Choose your question count and difficulty, then start. After you pick an answer, click _Reveal explanation_ to see the full step-by-step solution — answers never show automatically. Your score and a breakdown by drug type appear at the end so you know exactly where to focus. ⓘ This lesson has 44 questions in the bank. A 10-question quiz draws a random subset. Run multiple sets to see all 44 over time. How many questions? 10 20 30 Question difficulty Random mix Easy only Medium only Hard only Options Randomize question order Shuffle every time you start Timed mode 45-second countdown per question Number of sets Each set draws a fresh question pool. Great for drilling. − 1 + 10 Questions 1 Sets 10 Total Qs ~10 min Est. time ▶  Start quiz — Day Supply Question 1 of 10 0 correct · 0 skipped \--% Score Quiz complete! Lesson 3 · Day Supply Calculations · AlabamaPharmTech.com \-- Correct \-- Wrong \-- Skipped \-- Time Performance by question type \--% Overall accuracy \-- Weakest drug type Most missed question types Retry missed + skipped Next set New quiz Answer review — every question this session [Home](/) [Back to Dashboard](/modules) Previous [Back to Course](/pharmacy-math-practice) Lesson 3 of 6 Next lesson