Chapter 1 —Medication Orders & Tablet
Calculations
Stem: A provider orders cefazolin 0.75 g IV. The pharmacy
supplies 250 mg vials. How many vials should the nurse
prepare?
Options:
A. 2 vials
B. 3 vials
C. 4 vials
D. 6 vials
Correct Answer: B
Rationales:
, • Correct (B): Convert grams to milligrams: 0.75 g = 0.75 ×
1000 = 750 mg. Number of vials = ordered dose ÷ mg per
vial = 750 mg ÷ 250 mg/vial = 3 vials.
• A (2 vials): Reflects under-calculation (250 mg × 2 = 500
mg), failing to convert grams to mg or dividing incorrectly.
• C (4 vials): Reflects overestimation (250 mg × 4 = 1000
mg), likely from misreading 0.75 g as 1.0 g.
• D (6 vials): Reflects decimal-place error (thinking 0.75 g =
7500 mg) or multiplying by 10.
Teaching Point: Always convert units first; 0.75 g = 750 mg
before dividing by vial strength.
2.
Chapter Reference: Chapter 1 — Section 1.2: Metric Units,
Leading Zeros, and Microgram/milligram Conversions
Stem: Digoxin ordered 0.125 mg PO. Available tablets are 125
mcg each. How many tablets should be given?
Options:
A. 0.125 tablet
B. 1 tablet
C. 0.5 tablet
D. 2 tablets
Correct Answer: B
Rationales:
, • Correct (B): Convert mg to mcg: 0.125 mg = 0.125 × 1000 =
125 mcg. Therefore, 125 mcg ÷ 125 mcg/tablet = 1 tablet.
• A (0.125 tablet): Mistakenly treats milligram value as
tablet fraction without converting units.
• C (0.5 tablet): Likely result of dividing 125 mcg by 250 mcg
(wrong tablet strength) or halving incorrectly.
• D (2 tablets): Reflects confusion of mcg vs mg (thinking
0.125 mg = 250 mcg).
Teaching Point: Convert mg↔mcg before calculating
tablets.
3.
Chapter Reference: Chapter 1 — Section 1.3: Dosage from
Strength per Volume (mg/mL)
Stem: Order: give 75 mg of medication. Vial label: 150 mg per 2
mL. How many mL will the nurse administer?
Options:
A. 0.5 mL
B. 1 mL
C. 1.5 mL
D. 2 mL
Correct Answer: B
Rationales:
• Correct (B): Use ratio: (Ordered ÷ On-hand) × volume = (75
mg ÷ 150 mg) × 2 mL = 0.5 × 2 = 1 mL.
, • A (0.5 mL): Mistakenly used ordered ÷ on-hand without
multiplying by volume: 75 ÷ 150 = 0.5 (forgot ×2 mL).
• C (1.5 mL): Likely arithmetic error (adding instead of
multiplying) or using 75/50.
• D (2 mL): Assumes full vial is needed; fails to scale dose
proportionally.
Teaching Point: Always apply (ordered ÷ strength) ×
volume to find mL.
4.
Chapter Reference: Chapter 1 — Section 1.4: Infusion Safety —
Calculating mL/hr for Continuous Infusions
Stem: NS 1000 mL is to infuse over 8 hours. What mL/hr should
the pump be set to?
Options:
A. 100 mL/hr
B. 125 mL/hr
C. 150 mL/hr
D. 80 mL/hr
Correct Answer: B
Rationales:
• Correct (B): mL/hr = total volume ÷ hours = 1000 mL ÷ 8 hr
= 125 mL/hr.
• A (100 mL/hr): Error from dividing by 10 instead of 8 (1000
÷ 10 = 100).
Calculations
Stem: A provider orders cefazolin 0.75 g IV. The pharmacy
supplies 250 mg vials. How many vials should the nurse
prepare?
Options:
A. 2 vials
B. 3 vials
C. 4 vials
D. 6 vials
Correct Answer: B
Rationales:
, • Correct (B): Convert grams to milligrams: 0.75 g = 0.75 ×
1000 = 750 mg. Number of vials = ordered dose ÷ mg per
vial = 750 mg ÷ 250 mg/vial = 3 vials.
• A (2 vials): Reflects under-calculation (250 mg × 2 = 500
mg), failing to convert grams to mg or dividing incorrectly.
• C (4 vials): Reflects overestimation (250 mg × 4 = 1000
mg), likely from misreading 0.75 g as 1.0 g.
• D (6 vials): Reflects decimal-place error (thinking 0.75 g =
7500 mg) or multiplying by 10.
Teaching Point: Always convert units first; 0.75 g = 750 mg
before dividing by vial strength.
2.
Chapter Reference: Chapter 1 — Section 1.2: Metric Units,
Leading Zeros, and Microgram/milligram Conversions
Stem: Digoxin ordered 0.125 mg PO. Available tablets are 125
mcg each. How many tablets should be given?
Options:
A. 0.125 tablet
B. 1 tablet
C. 0.5 tablet
D. 2 tablets
Correct Answer: B
Rationales:
, • Correct (B): Convert mg to mcg: 0.125 mg = 0.125 × 1000 =
125 mcg. Therefore, 125 mcg ÷ 125 mcg/tablet = 1 tablet.
• A (0.125 tablet): Mistakenly treats milligram value as
tablet fraction without converting units.
• C (0.5 tablet): Likely result of dividing 125 mcg by 250 mcg
(wrong tablet strength) or halving incorrectly.
• D (2 tablets): Reflects confusion of mcg vs mg (thinking
0.125 mg = 250 mcg).
Teaching Point: Convert mg↔mcg before calculating
tablets.
3.
Chapter Reference: Chapter 1 — Section 1.3: Dosage from
Strength per Volume (mg/mL)
Stem: Order: give 75 mg of medication. Vial label: 150 mg per 2
mL. How many mL will the nurse administer?
Options:
A. 0.5 mL
B. 1 mL
C. 1.5 mL
D. 2 mL
Correct Answer: B
Rationales:
• Correct (B): Use ratio: (Ordered ÷ On-hand) × volume = (75
mg ÷ 150 mg) × 2 mL = 0.5 × 2 = 1 mL.
, • A (0.5 mL): Mistakenly used ordered ÷ on-hand without
multiplying by volume: 75 ÷ 150 = 0.5 (forgot ×2 mL).
• C (1.5 mL): Likely arithmetic error (adding instead of
multiplying) or using 75/50.
• D (2 mL): Assumes full vial is needed; fails to scale dose
proportionally.
Teaching Point: Always apply (ordered ÷ strength) ×
volume to find mL.
4.
Chapter Reference: Chapter 1 — Section 1.4: Infusion Safety —
Calculating mL/hr for Continuous Infusions
Stem: NS 1000 mL is to infuse over 8 hours. What mL/hr should
the pump be set to?
Options:
A. 100 mL/hr
B. 125 mL/hr
C. 150 mL/hr
D. 80 mL/hr
Correct Answer: B
Rationales:
• Correct (B): mL/hr = total volume ÷ hours = 1000 mL ÷ 8 hr
= 125 mL/hr.
• A (100 mL/hr): Error from dividing by 10 instead of 8 (1000
÷ 10 = 100).
