DOSAGE CALCULATIONS MADE
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Topic: Dimensional Analysis Fundamentals
The healthcare provider orders cephalexin 0.5 g PO. The
pharmacy dispenses cephalexin 250 mg/5 mL. How many
milliliters will the nurse administer per dose?
A. 5 mL
B. 10 mL
C. 15 mL
D. 20 mL
Correct Answer: B
Rationale:
Step 1: Identify the goal. The desired amount is 0.5 g, but the
medication is available in mg. The first step is to convert the
ordered dose to the same unit as the available concentration.
Step 2: Set up the dimensional analysis equation to cancel units.
0.5 g1×1000 mg1 g×5 mL250 mg= mL per dose10.5 g
×1 g1000 mg×250 mg5 mL= mL per dose
Step 3: Cancel the units "g" and "mg".
0.5×1000×5250 mL=2500250 mL=10 mL2500.5×1000×5
mL=2502500 mL=10 mL
The nurse will administer 10 mL.
,Medication Safety Note: Always verify that the units of the
medication order match the units on the medication label.
Convert to the same unit before calculating to prevent a tenfold
or greater dosing error.
Question 2
Topic: Oral Dosage Calculations
The prescriber orders digoxin 0.125 mg PO daily. The pharmacy
supplies digoxin 62.5 mcg tablets. How many tablets will the
nurse administer?
A. 0.5 tablet
B. 1 tablet
C. 1.5 tablets
D. 2 tablets
Correct Answer: D
Rationale:
Step 1: Convert the ordered dose from mg to mcg to match the
available tablet strength.
Step 2: Use dimensional analysis to find the number of tablets.
0.125 mg1×1000 mcg1 mg×1 tablet62.5 mcg= tablets10.125 mg
×1 mg1000 mcg×62.5 mcg1 tablet= tablets
Step 3: Cancel the units "mg" and "mcg".
, 0.125×100062.5 tablets=12562.5 tablets=2 tablets62.50.125×10
00 tablets=62.5125 tablets=2 tablets
The nurse will administer 2 tablets.
Medication Safety Note: Digoxin has a narrow therapeutic
index. Accurate calculation and administration are critical to
prevent toxicity. Always use a leading zero for doses less than 1
(e.g., 0.125 mg) and never use a trailing zero.
Question 3
Topic: Injectable Medications
A patient is to receive furosemide 80 mg IV push. The vial
contains furosemide 40 mg/4 mL. How many mL will the nurse
administer?
A. 2 mL
B. 4 mL
C. 6 mL
D. 8 mL
Correct Answer: D
Rationale:
Step 1: Determine the desired dose and the available
concentration.
Step 2: Set up the dimensional analysis equation.
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Topic: Dimensional Analysis Fundamentals
The healthcare provider orders cephalexin 0.5 g PO. The
pharmacy dispenses cephalexin 250 mg/5 mL. How many
milliliters will the nurse administer per dose?
A. 5 mL
B. 10 mL
C. 15 mL
D. 20 mL
Correct Answer: B
Rationale:
Step 1: Identify the goal. The desired amount is 0.5 g, but the
medication is available in mg. The first step is to convert the
ordered dose to the same unit as the available concentration.
Step 2: Set up the dimensional analysis equation to cancel units.
0.5 g1×1000 mg1 g×5 mL250 mg= mL per dose10.5 g
×1 g1000 mg×250 mg5 mL= mL per dose
Step 3: Cancel the units "g" and "mg".
0.5×1000×5250 mL=2500250 mL=10 mL2500.5×1000×5
mL=2502500 mL=10 mL
The nurse will administer 10 mL.
,Medication Safety Note: Always verify that the units of the
medication order match the units on the medication label.
Convert to the same unit before calculating to prevent a tenfold
or greater dosing error.
Question 2
Topic: Oral Dosage Calculations
The prescriber orders digoxin 0.125 mg PO daily. The pharmacy
supplies digoxin 62.5 mcg tablets. How many tablets will the
nurse administer?
A. 0.5 tablet
B. 1 tablet
C. 1.5 tablets
D. 2 tablets
Correct Answer: D
Rationale:
Step 1: Convert the ordered dose from mg to mcg to match the
available tablet strength.
Step 2: Use dimensional analysis to find the number of tablets.
0.125 mg1×1000 mcg1 mg×1 tablet62.5 mcg= tablets10.125 mg
×1 mg1000 mcg×62.5 mcg1 tablet= tablets
Step 3: Cancel the units "mg" and "mcg".
, 0.125×100062.5 tablets=12562.5 tablets=2 tablets62.50.125×10
00 tablets=62.5125 tablets=2 tablets
The nurse will administer 2 tablets.
Medication Safety Note: Digoxin has a narrow therapeutic
index. Accurate calculation and administration are critical to
prevent toxicity. Always use a leading zero for doses less than 1
(e.g., 0.125 mg) and never use a trailing zero.
Question 3
Topic: Injectable Medications
A patient is to receive furosemide 80 mg IV push. The vial
contains furosemide 40 mg/4 mL. How many mL will the nurse
administer?
A. 2 mL
B. 4 mL
C. 6 mL
D. 8 mL
Correct Answer: D
Rationale:
Step 1: Determine the desired dose and the available
concentration.
Step 2: Set up the dimensional analysis equation.
