Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
1) Tablet conversion — simple
Order: Amoxicillin 750 mg PO. Available: 250 mg
tablets. How many tablets?
Answer: 3 tablets
Work: 750 mg ÷ 250 mg/tablet = 3.
Rationale: Divide ordered dose by strength per tablet.
2) mg → g conversion
Order: Cefazolin 1.5 g IV. Available vial labeled 500 mg/mL. How many mL to give?
Answer: 3 mL
Work: 1.5 g = 1500 mg. 1500 mg ÷ (500 mg/mL) = 3 mL.
Rationale: Convert grams to mg, then divide by concentration.
3) Pediatric mg/kg
Order: Gentamicin 5 mg/kg IV once. Child weighs 18 kg. Available: gentamicin 40 mg/mL. How
many mL to administer?
Answer: 2.25 mL
Work: Dose = 5 mg/kg × 18 kg = 90 mg. Volume = 90 mg ÷ (40 mg/mL) = 2.25
mL. Rationale: mg/kg → total mg, then concentration → mL.
4) Tablet fraction — partial tablet allowed
Order: Propranolol 37.5 mg PO. Available: 75 mg tablets. How many tablets?
,Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
Answer: 0.5 tablet (half)
Work: 37.5 ÷ 75 = 0.5.
Rationale: Give half of 75 mg tablet.
5) Liquid dose calculation (mL)
Order: Ondansetron 4 mg PO. Available oral solution: 2 mg/5 mL. How many mL?
Answer: 10 mL
Work: 2 mg per 5 mL → 0.4 mg/mL. Alternatively: (5 mL/2 mg) × 4 mg = 10 mL.
Rationale: Use ratio: 4 mg × (5 mL / 2 mg) = 10 mL.
6) IV flow rate — mL/hr
Order: Infuse 1000 mL NS over 8 hours. Rate in mL/hr?
Answer: 125 mL/hr
Work: 1000 mL ÷ 8 hr = 125 mL/hr.
Rationale: Total volume ÷ hours = mL/hr.
7) IV flow rate — gtt/min
Order: Infuse 750 mL D5W over 6 hours using tubing with 15 gtt/mL. What rate in gtt/min?
Answer: 31 gtt/min
Work: mL/hr = 750 ÷ 6 = 125 mL/hr. mL/min = 125 ÷ 60 = 2.0833 mL/min. gtt/min = 2.0833 × 15
= 31.25
→ 31 gtt/min (round to nearest whole
drop). Rationale: (Volume/hr ÷ 60) ×
drops/mL.
,Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
8) mcg/kg/min titration → mL/hr
Order: Dopamine 5 mcg/kg/min for a 70-kg patient. Concentration: 400 mg in 250 mL (label:
400 mg/250 mL). What is mL/hr?
Note: convert mcg to mg (1,000 mcg = 1 mg).
Answer: 26 mL/hr
Work (stepwise):
Dose mcg/min = 5 mcg × 70 kg = 350 mcg/min.
Convert to mg/min: 350 mcg ÷ 1000 = 0.35 mg/min.
mg/hr = 0.35 × 60 = 21 mg/hr.
Concentration = 400 mg / 250 mL = 1.6 mg/mL.
mL/hr = 21 mg/hr ÷ 1.6 mg/mL = 13.125 mL/hr.
Wait — check arithmetic: The last step indicates 13.125 mL/hr. But earlier in our smaller set we
used 10 mcg/kg/min giving different. Let's recalc carefully:
Hold on—recompute completely and correctly:
5 mcg/kg/min × 70 kg = 350 mcg/min.
350 mcg/min = 0.35 mg/min.
mg/hr = 0.35 × 60 = 21 mg/hr.
, Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
Concentration = 400 mg / 250 mL = 1.6 mg/mL.
mL/hr = 21 ÷ 1.6 = 13.125 mL/hr → round to 13.1 mL/hr (or 13 mL/hr on pump, depending on
policy).
Correct Answer (final): 13.1 mL/hr (round to 13 mL/hr if required by pump)
Rationale: Convert mcg→mg, min→hr, then divide by mg/mL.
(Note: if your pump requires whole mL/hr, round per facility policy — most facilities round to
nearest tenth or whole number.)
9) Reconstitution — pediatric
Vial: Ampicillin 250 mg per vial (dry). Add 2.5 mL sterile water to reconstitute → yields
concentration 100 mg/mL. The order: Ampicillin 150 mg IV. How many mL will you give?
Answer: 1.5 mL
Work: Concentration 100 mg/mL. 150 mg ÷ 100 mg/mL = 1.5
mL. Rationale: After reconstitution, use mg/mL concentration.
10) Insulin unit conversion (U)
Order: Regular insulin 8 units IV now. Available vial: U-100 (100 units per 1 mL). How many mL to
draw?
Answer: 0.08 mL
Work: 8 units × (1 mL / 100 units) = 0.08
mL. Rationale: U-100 standard: 1 unit =
0.01 mL.
11) Sliding scale — oral insulin correction
Question Dosage Exam Practice Set |
Complete Questions and Answers
1) Tablet conversion — simple
Order: Amoxicillin 750 mg PO. Available: 250 mg
tablets. How many tablets?
Answer: 3 tablets
Work: 750 mg ÷ 250 mg/tablet = 3.
Rationale: Divide ordered dose by strength per tablet.
2) mg → g conversion
Order: Cefazolin 1.5 g IV. Available vial labeled 500 mg/mL. How many mL to give?
Answer: 3 mL
Work: 1.5 g = 1500 mg. 1500 mg ÷ (500 mg/mL) = 3 mL.
Rationale: Convert grams to mg, then divide by concentration.
3) Pediatric mg/kg
Order: Gentamicin 5 mg/kg IV once. Child weighs 18 kg. Available: gentamicin 40 mg/mL. How
many mL to administer?
Answer: 2.25 mL
Work: Dose = 5 mg/kg × 18 kg = 90 mg. Volume = 90 mg ÷ (40 mg/mL) = 2.25
mL. Rationale: mg/kg → total mg, then concentration → mL.
4) Tablet fraction — partial tablet allowed
Order: Propranolol 37.5 mg PO. Available: 75 mg tablets. How many tablets?
,Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
Answer: 0.5 tablet (half)
Work: 37.5 ÷ 75 = 0.5.
Rationale: Give half of 75 mg tablet.
5) Liquid dose calculation (mL)
Order: Ondansetron 4 mg PO. Available oral solution: 2 mg/5 mL. How many mL?
Answer: 10 mL
Work: 2 mg per 5 mL → 0.4 mg/mL. Alternatively: (5 mL/2 mg) × 4 mg = 10 mL.
Rationale: Use ratio: 4 mg × (5 mL / 2 mg) = 10 mL.
6) IV flow rate — mL/hr
Order: Infuse 1000 mL NS over 8 hours. Rate in mL/hr?
Answer: 125 mL/hr
Work: 1000 mL ÷ 8 hr = 125 mL/hr.
Rationale: Total volume ÷ hours = mL/hr.
7) IV flow rate — gtt/min
Order: Infuse 750 mL D5W over 6 hours using tubing with 15 gtt/mL. What rate in gtt/min?
Answer: 31 gtt/min
Work: mL/hr = 750 ÷ 6 = 125 mL/hr. mL/min = 125 ÷ 60 = 2.0833 mL/min. gtt/min = 2.0833 × 15
= 31.25
→ 31 gtt/min (round to nearest whole
drop). Rationale: (Volume/hr ÷ 60) ×
drops/mL.
,Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
8) mcg/kg/min titration → mL/hr
Order: Dopamine 5 mcg/kg/min for a 70-kg patient. Concentration: 400 mg in 250 mL (label:
400 mg/250 mL). What is mL/hr?
Note: convert mcg to mg (1,000 mcg = 1 mg).
Answer: 26 mL/hr
Work (stepwise):
Dose mcg/min = 5 mcg × 70 kg = 350 mcg/min.
Convert to mg/min: 350 mcg ÷ 1000 = 0.35 mg/min.
mg/hr = 0.35 × 60 = 21 mg/hr.
Concentration = 400 mg / 250 mL = 1.6 mg/mL.
mL/hr = 21 mg/hr ÷ 1.6 mg/mL = 13.125 mL/hr.
Wait — check arithmetic: The last step indicates 13.125 mL/hr. But earlier in our smaller set we
used 10 mcg/kg/min giving different. Let's recalc carefully:
Hold on—recompute completely and correctly:
5 mcg/kg/min × 70 kg = 350 mcg/min.
350 mcg/min = 0.35 mg/min.
mg/hr = 0.35 × 60 = 21 mg/hr.
, Fundamentals Math Dosage Calculation | 100-
Question Dosage Exam Practice Set |
Complete Questions and Answers
Concentration = 400 mg / 250 mL = 1.6 mg/mL.
mL/hr = 21 ÷ 1.6 = 13.125 mL/hr → round to 13.1 mL/hr (or 13 mL/hr on pump, depending on
policy).
Correct Answer (final): 13.1 mL/hr (round to 13 mL/hr if required by pump)
Rationale: Convert mcg→mg, min→hr, then divide by mg/mL.
(Note: if your pump requires whole mL/hr, round per facility policy — most facilities round to
nearest tenth or whole number.)
9) Reconstitution — pediatric
Vial: Ampicillin 250 mg per vial (dry). Add 2.5 mL sterile water to reconstitute → yields
concentration 100 mg/mL. The order: Ampicillin 150 mg IV. How many mL will you give?
Answer: 1.5 mL
Work: Concentration 100 mg/mL. 150 mg ÷ 100 mg/mL = 1.5
mL. Rationale: After reconstitution, use mg/mL concentration.
10) Insulin unit conversion (U)
Order: Regular insulin 8 units IV now. Available vial: U-100 (100 units per 1 mL). How many mL to
draw?
Answer: 0.08 mL
Work: 8 units × (1 mL / 100 units) = 0.08
mL. Rationale: U-100 standard: 1 unit =
0.01 mL.
11) Sliding scale — oral insulin correction
