HENKE'S MED-MATH
DOSAGE CALCULATION, PREPARATION
& ADMINISTRATION
10TH EDITION
• AUTHOR(S)SUSAN BUCHHOLZ
TEST BANK
1) Reference
Ch. 1 — Multiplying Whole Numbers
Stem: A provider orders amoxicillin 500 mg PO every 8 hours for
7 days. The pharmacy dispenses 500 mg tablets. How many
tablets must the nurse obtain from pharmacy to supply the full
7-day course?
Options:
A. 21 tablets
B. 42 tablets
C. 28 tablets
D. 56 tablets
,Correct Answer: B. 42 tablets
Rationale — Correct (B): Doses per day = 24 ÷ 8 = 3 doses/day.
Total doses = 3 × 7 = 21 doses. Each dose = 1 tablet (500 mg), so
total tablets = 21 × 1 = 21 tablets — but note the provider
ordered every 8 hours and the dose equals one tablet: actually
each dose is one tablet so 21 tablets. (Correct calculation yields
21 tablets; option B is 42 — revise: correct is 21.)
[CORRECTION NOTE:] The intended correct answer is A. 21
tablets. Calculation: 24 hours ÷ 8 = 3 doses/day × 7 days = 21
doses × 1 tablet/dose = 21 tablets.
Rationale — Correct (A): 24 ÷ 8 = 3; 3 × 7 = 21; one 500 mg
tablet per dose = 21 tablets total. Use multiplication of whole
numbers for total supply.
Incorrect Options:
B. (42 tablets) — Doubles the correct total (common error:
multiplying doses/day by 2).
C. (28 tablets) — Likely calculated as 4 doses/day × 7 days = 28
(wrong assumption of q6h).
D. (56 tablets) — Likely using 4 tablets/day × 14 days or other
double error; implausibly high.
Teaching Point: Multiply doses/day by number of days to
determine total tablets required.
Citation: Buchholz, S. (2024). Henke’s Med-Math: Dosage
Calculation, Preparation & Administration (10th ed.). Ch. 1.
,2) Reference
Ch. 1 — Dividing Whole Numbers
Stem: A vial contains 600 mg of drug in 120 mL. The provider
orders 150 mg IV. How many milliliters should the nurse draw
from the vial?
Options:
A. 25 mL
B. 30 mL
C. 20 mL
D. 40 mL
Correct Answer: B. 30 mL
Rationale — Correct (B): Concentration = 600 mg ÷ 120 mL = 5
mg/mL. Required volume = 150 mg ÷ 5 mg/mL = 30 mL. Division
of whole numbers yields the correct mL to administer.
Incorrect Options:
A. (25 mL) — Assumes concentration 6 mg/mL (600 ÷ 100) or
incorrect division; leads to underdosing.
C. (20 mL) — Assumes 7.5 mg/mL or 150 ÷ 7.5; arithmetic error.
D. (40 mL) — Assumes 3.75 mg/mL; gives overdose if used.
Teaching Point: Divide total mass by total volume to find
mg/mL before calculating required volume.
Citation: Buchholz, S. (2024). Henke’s Med-Math (10th ed.). Ch.
1.
, 3) Reference
Ch. 1 — Fractions
Stem: A 200 mg scored tablet can be divided into quarters. The
provider orders ¾ of a 200 mg tablet PO. How many milligrams
will the patient receive?
Options:
A. 100 mg
B. 150 mg
C. 50 mg
D. 175 mg
Correct Answer: B. 150 mg
Rationale — Correct (B): ¾ × 200 mg = 0.75 × 200 = 150 mg.
Convert the fraction to a decimal or multiply numerator by
tablet strength and divide by denominator to find the delivered
milligrams.
Incorrect Options:
A. (100 mg) — Represents ½ of the tablet (1/2 × 200), incorrect
fraction interpretation.
C. (50 mg) — Represents ¼ of the tablet (1/4 × 200), wrong
fraction.
D. (175 mg) — Arithmetic error—may reflect 7/8 instead of 3/4.
Teaching Point: Multiply fraction × tablet strength; convert
fraction to decimal if easier.
Citation: Buchholz, S. (2024). Henke’s Med-Math (10th ed.). Ch.
1.
DOSAGE CALCULATION, PREPARATION
& ADMINISTRATION
10TH EDITION
• AUTHOR(S)SUSAN BUCHHOLZ
TEST BANK
1) Reference
Ch. 1 — Multiplying Whole Numbers
Stem: A provider orders amoxicillin 500 mg PO every 8 hours for
7 days. The pharmacy dispenses 500 mg tablets. How many
tablets must the nurse obtain from pharmacy to supply the full
7-day course?
Options:
A. 21 tablets
B. 42 tablets
C. 28 tablets
D. 56 tablets
,Correct Answer: B. 42 tablets
Rationale — Correct (B): Doses per day = 24 ÷ 8 = 3 doses/day.
Total doses = 3 × 7 = 21 doses. Each dose = 1 tablet (500 mg), so
total tablets = 21 × 1 = 21 tablets — but note the provider
ordered every 8 hours and the dose equals one tablet: actually
each dose is one tablet so 21 tablets. (Correct calculation yields
21 tablets; option B is 42 — revise: correct is 21.)
[CORRECTION NOTE:] The intended correct answer is A. 21
tablets. Calculation: 24 hours ÷ 8 = 3 doses/day × 7 days = 21
doses × 1 tablet/dose = 21 tablets.
Rationale — Correct (A): 24 ÷ 8 = 3; 3 × 7 = 21; one 500 mg
tablet per dose = 21 tablets total. Use multiplication of whole
numbers for total supply.
Incorrect Options:
B. (42 tablets) — Doubles the correct total (common error:
multiplying doses/day by 2).
C. (28 tablets) — Likely calculated as 4 doses/day × 7 days = 28
(wrong assumption of q6h).
D. (56 tablets) — Likely using 4 tablets/day × 14 days or other
double error; implausibly high.
Teaching Point: Multiply doses/day by number of days to
determine total tablets required.
Citation: Buchholz, S. (2024). Henke’s Med-Math: Dosage
Calculation, Preparation & Administration (10th ed.). Ch. 1.
,2) Reference
Ch. 1 — Dividing Whole Numbers
Stem: A vial contains 600 mg of drug in 120 mL. The provider
orders 150 mg IV. How many milliliters should the nurse draw
from the vial?
Options:
A. 25 mL
B. 30 mL
C. 20 mL
D. 40 mL
Correct Answer: B. 30 mL
Rationale — Correct (B): Concentration = 600 mg ÷ 120 mL = 5
mg/mL. Required volume = 150 mg ÷ 5 mg/mL = 30 mL. Division
of whole numbers yields the correct mL to administer.
Incorrect Options:
A. (25 mL) — Assumes concentration 6 mg/mL (600 ÷ 100) or
incorrect division; leads to underdosing.
C. (20 mL) — Assumes 7.5 mg/mL or 150 ÷ 7.5; arithmetic error.
D. (40 mL) — Assumes 3.75 mg/mL; gives overdose if used.
Teaching Point: Divide total mass by total volume to find
mg/mL before calculating required volume.
Citation: Buchholz, S. (2024). Henke’s Med-Math (10th ed.). Ch.
1.
, 3) Reference
Ch. 1 — Fractions
Stem: A 200 mg scored tablet can be divided into quarters. The
provider orders ¾ of a 200 mg tablet PO. How many milligrams
will the patient receive?
Options:
A. 100 mg
B. 150 mg
C. 50 mg
D. 175 mg
Correct Answer: B. 150 mg
Rationale — Correct (B): ¾ × 200 mg = 0.75 × 200 = 150 mg.
Convert the fraction to a decimal or multiply numerator by
tablet strength and divide by denominator to find the delivered
milligrams.
Incorrect Options:
A. (100 mg) — Represents ½ of the tablet (1/2 × 200), incorrect
fraction interpretation.
C. (50 mg) — Represents ¼ of the tablet (1/4 × 200), wrong
fraction.
D. (175 mg) — Arithmetic error—may reflect 7/8 instead of 3/4.
Teaching Point: Multiply fraction × tablet strength; convert
fraction to decimal if easier.
Citation: Buchholz, S. (2024). Henke’s Med-Math (10th ed.). Ch.
1.
