Nursing Math Made Simple: Safe Dose, IV
Drip, and Pediatric Calculations
Basic Dose Calculations
Question 1
A patient needs 250 mg of medication. The available tablets are 125 mg each. How many
tablets should be administered?
Answer: 2 tablets
Explanation: Use the formula: Desired dose ÷ Available dose = Number of tablets 250 mg ÷
125 mg = 2 tablets
Question 2
Order: Amoxicillin 500 mg PO q8h. Available: Amoxicillin 250 mg capsules. How many
capsules per dose?
Answer: 2 capsules
Explanation: 500 mg (desired) ÷ 250 mg (available) = 2 capsules per dose
Question 3
A physician orders 0.75 mg of digoxin. Available tablets are 0.25 mg. How many tablets
needed?
Answer: 3 tablets
Explanation: 0.75 mg ÷ 0.25 mg = 3 tablets
Question 4
Order: Furosemide 80 mg PO daily. Available: 40 mg tablets. Calculate the number of
tablets.
Answer: 2 tablets
Explanation: 80 mg ÷ 40 mg = 2 tablets daily
Question 5
A patient requires 1.5 g of medication. Available: 500 mg tablets. How many tablets?
,Answer: 3 tablets
Explanation: First convert: 1.5 g = 1500 mg. Then: 1500 mg ÷ 500 mg = 3 tablets
Question 6
Order: Acetaminophen 650 mg. Available: 325 mg tablets. How many tablets?
Answer: 2 tablets
Explanation: 650 mg ÷ 325 mg = 2 tablets
Question 7
A patient needs 0.125 mg of medication. Available: 0.25 mg tablets (scored). How many
tablets?
Answer: 0.5 tablets (½ tablet)
Explanation: 0.125 mg ÷ 0.25 mg = 0.5 tablets. Since the tablet is scored, it can be split in
half.
Question 8
Order: Prednisone 15 mg daily. Available: 5 mg tablets. Calculate tablets needed.
Answer: 3 tablets
Explanation: 15 mg ÷ 5 mg = 3 tablets
Question 9
A physician orders 0.4 mg of medication. Available: 0.2 mg tablets. How many tablets?
Answer: 2 tablets
Explanation: 0.4 mg ÷ 0.2 mg = 2 tablets
Question 10
Order: Metformin 1000 mg BID. Available: 500 mg tablets. How many tablets per dose?
Answer: 2 tablets per dose
Explanation: 1000 mg ÷ 500 mg = 2 tablets per dose (BID means twice daily)
Question 11
A patient needs 30 mg of medication. Available: 15 mg/5 mL liquid. How many mL?
,Answer: 10 mL
Explanation: Use proportion: 15 mg : 5 mL = 30 mg : x mL Cross multiply: 15x = 150, x =
10 mL
Question 12
Order: Potassium chloride 40 mEq. Available: 20 mEq/15 mL. Calculate mL needed.
Answer: 30 mL
Explanation: 20 mEq : 15 mL = 40 mEq : x mL Cross multiply: 20x = 600, x = 30 mL
Question 13
A patient requires 75 mg of liquid medication. Available: 25 mg/5 mL. How many mL?
Answer: 15 mL
Explanation: 25 mg : 5 mL = 75 mg : x mL Cross multiply: 25x = 375, x = 15 mL
Question 14
Order: Amoxicillin suspension 400 mg. Available: 250 mg/5 mL. Calculate mL needed.
Answer: 8 mL
Explanation: 250 mg : 5 mL = 400 mg : x mL Cross multiply: 250x = 2000, x = 8 mL
Question 15
A physician orders 0.5 mg of medication. Available: 0.25 mg/mL. How many mL?
Answer: 2 mL
Explanation: 0.25 mg : 1 mL = 0.5 mg : x mL Cross multiply: 0.25x = 0.5, x = 2 mL
IV Drip Rate Calculations
Question 16
Order: 1000 mL D5W to infuse over 8 hours. Drop factor: 15 gtt/mL. Calculate drops per
minute.
Answer: 31 gtt/min
, Explanation: Formula: (Volume × Drop factor) ÷ (Time in minutes) (1000 × 15) ÷ (8 × 60)
= 15000 ÷ 480 = 31.25 ≈ 31 gtt/min
Question 17
A patient needs 500 mL NS over 4 hours. Drop factor: 20 gtt/mL. Calculate gtt/min.
Answer: 42 gtt/min
Explanation: (500 × 20) ÷ (4 × 60) = 10000 ÷ 240 = 41.67 ≈ 42 gtt/min
Question 18
Order: 250 mL to infuse over 2 hours. Drop factor: 10 gtt/mL. Calculate drops per minute.
Answer: 21 gtt/min
Explanation: (250 × 10) ÷ (2 × 60) = 2500 ÷ 120 = 20.83 ≈ 21 gtt/min
Question 19
Infuse 1500 mL over 12 hours using a 15 gtt/mL set. Calculate gtt/min.
Answer: 31 gtt/min
Explanation: (1500 × 15) ÷ (12 × 60) = 22500 ÷ 720 = 31.25 ≈ 31 gtt/min
Question 20
Order: 100 mL to run over 30 minutes. Drop factor: 60 gtt/mL. Calculate gtt/min.
Answer: 200 gtt/min
Explanation: (100 × 60) ÷ 30 = 6000 ÷ 30 = 200 gtt/min
Question 21
A patient receives 750 mL over 6 hours. Drop factor: 12 gtt/mL. Calculate drops per minute.
Answer: 25 gtt/min
Explanation: (750 × 12) ÷ (6 × 60) = 9000 ÷ 360 = 25 gtt/min
Question 22
Order: 2000 mL D5½NS over 24 hours. Drop factor: 15 gtt/mL. Calculate gtt/min.
Answer: 21 gtt/min
Drip, and Pediatric Calculations
Basic Dose Calculations
Question 1
A patient needs 250 mg of medication. The available tablets are 125 mg each. How many
tablets should be administered?
Answer: 2 tablets
Explanation: Use the formula: Desired dose ÷ Available dose = Number of tablets 250 mg ÷
125 mg = 2 tablets
Question 2
Order: Amoxicillin 500 mg PO q8h. Available: Amoxicillin 250 mg capsules. How many
capsules per dose?
Answer: 2 capsules
Explanation: 500 mg (desired) ÷ 250 mg (available) = 2 capsules per dose
Question 3
A physician orders 0.75 mg of digoxin. Available tablets are 0.25 mg. How many tablets
needed?
Answer: 3 tablets
Explanation: 0.75 mg ÷ 0.25 mg = 3 tablets
Question 4
Order: Furosemide 80 mg PO daily. Available: 40 mg tablets. Calculate the number of
tablets.
Answer: 2 tablets
Explanation: 80 mg ÷ 40 mg = 2 tablets daily
Question 5
A patient requires 1.5 g of medication. Available: 500 mg tablets. How many tablets?
,Answer: 3 tablets
Explanation: First convert: 1.5 g = 1500 mg. Then: 1500 mg ÷ 500 mg = 3 tablets
Question 6
Order: Acetaminophen 650 mg. Available: 325 mg tablets. How many tablets?
Answer: 2 tablets
Explanation: 650 mg ÷ 325 mg = 2 tablets
Question 7
A patient needs 0.125 mg of medication. Available: 0.25 mg tablets (scored). How many
tablets?
Answer: 0.5 tablets (½ tablet)
Explanation: 0.125 mg ÷ 0.25 mg = 0.5 tablets. Since the tablet is scored, it can be split in
half.
Question 8
Order: Prednisone 15 mg daily. Available: 5 mg tablets. Calculate tablets needed.
Answer: 3 tablets
Explanation: 15 mg ÷ 5 mg = 3 tablets
Question 9
A physician orders 0.4 mg of medication. Available: 0.2 mg tablets. How many tablets?
Answer: 2 tablets
Explanation: 0.4 mg ÷ 0.2 mg = 2 tablets
Question 10
Order: Metformin 1000 mg BID. Available: 500 mg tablets. How many tablets per dose?
Answer: 2 tablets per dose
Explanation: 1000 mg ÷ 500 mg = 2 tablets per dose (BID means twice daily)
Question 11
A patient needs 30 mg of medication. Available: 15 mg/5 mL liquid. How many mL?
,Answer: 10 mL
Explanation: Use proportion: 15 mg : 5 mL = 30 mg : x mL Cross multiply: 15x = 150, x =
10 mL
Question 12
Order: Potassium chloride 40 mEq. Available: 20 mEq/15 mL. Calculate mL needed.
Answer: 30 mL
Explanation: 20 mEq : 15 mL = 40 mEq : x mL Cross multiply: 20x = 600, x = 30 mL
Question 13
A patient requires 75 mg of liquid medication. Available: 25 mg/5 mL. How many mL?
Answer: 15 mL
Explanation: 25 mg : 5 mL = 75 mg : x mL Cross multiply: 25x = 375, x = 15 mL
Question 14
Order: Amoxicillin suspension 400 mg. Available: 250 mg/5 mL. Calculate mL needed.
Answer: 8 mL
Explanation: 250 mg : 5 mL = 400 mg : x mL Cross multiply: 250x = 2000, x = 8 mL
Question 15
A physician orders 0.5 mg of medication. Available: 0.25 mg/mL. How many mL?
Answer: 2 mL
Explanation: 0.25 mg : 1 mL = 0.5 mg : x mL Cross multiply: 0.25x = 0.5, x = 2 mL
IV Drip Rate Calculations
Question 16
Order: 1000 mL D5W to infuse over 8 hours. Drop factor: 15 gtt/mL. Calculate drops per
minute.
Answer: 31 gtt/min
, Explanation: Formula: (Volume × Drop factor) ÷ (Time in minutes) (1000 × 15) ÷ (8 × 60)
= 15000 ÷ 480 = 31.25 ≈ 31 gtt/min
Question 17
A patient needs 500 mL NS over 4 hours. Drop factor: 20 gtt/mL. Calculate gtt/min.
Answer: 42 gtt/min
Explanation: (500 × 20) ÷ (4 × 60) = 10000 ÷ 240 = 41.67 ≈ 42 gtt/min
Question 18
Order: 250 mL to infuse over 2 hours. Drop factor: 10 gtt/mL. Calculate drops per minute.
Answer: 21 gtt/min
Explanation: (250 × 10) ÷ (2 × 60) = 2500 ÷ 120 = 20.83 ≈ 21 gtt/min
Question 19
Infuse 1500 mL over 12 hours using a 15 gtt/mL set. Calculate gtt/min.
Answer: 31 gtt/min
Explanation: (1500 × 15) ÷ (12 × 60) = 22500 ÷ 720 = 31.25 ≈ 31 gtt/min
Question 20
Order: 100 mL to run over 30 minutes. Drop factor: 60 gtt/mL. Calculate gtt/min.
Answer: 200 gtt/min
Explanation: (100 × 60) ÷ 30 = 6000 ÷ 30 = 200 gtt/min
Question 21
A patient receives 750 mL over 6 hours. Drop factor: 12 gtt/mL. Calculate drops per minute.
Answer: 25 gtt/min
Explanation: (750 × 12) ÷ (6 × 60) = 9000 ÷ 360 = 25 gtt/min
Question 22
Order: 2000 mL D5½NS over 24 hours. Drop factor: 15 gtt/mL. Calculate gtt/min.
Answer: 21 gtt/min
