DOSAGE CALCULATIONS MADE
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Topic: Basic Arithmetic & Unit Conversions (Easy)
The nurse is preparing to administer famotidine 20 mg PO. The
medication is available as famotidine 40 mg/5 mL. How many
mL will the nurse administer?
A. 1 mL
B. 2.5 mL
C. 5 mL
D. 10 mL
Correct Answer: B. 2.5 mL
Rationale:
Step 1: Identify the desired amount and the available
concentration. The order is for 20 mg. The supply is 40 mg per 5
mL.
Step 2: Set up the dimensional-analysis equation to solve for
mL.
5 mL40 mg×20 mg= mL40 mg5 mL×20 mg= mL
Step 3: Cancel the common unit (mg) and solve.
5 mL40×20=10040 mL=2.5 mL405 mL×20=40100 mL=2.5 mL
Medication Safety Note: Always double-check your calculation,
especially with high-alert medications like anticoagulants or
,insulin. If the calculated dose seems significantly different from
usual doses, re-evaluate the order and your math. Use a second
nurse to verify calculations for high-risk medications.
Question 2
Topic: Oral Dosage Calculations (Easy)
The healthcare provider orders digoxin 0.125 mg PO daily. The
pharmacy provides digoxin 250 mcg tablets. How many tablets
will the nurse administer?
A. 0.25 tablets
B. 0.5 tablets
C. 1 tablet
D. 2 tablets
Correct Answer: B. 0.5 tablets
Rationale:
Step 1: Convert the ordered dose to the same unit as the
available tablet. The order is 0.125 mg, and the tablet is 250
mcg. Convert mg to mcg: 1 mg = 1000 mcg. So, 0.125 mg = 125
mcg.
Step 2: Set up the dimensional-analysis equation.
1 tablet250 mcg×1000 mcg1 mg×0.125 mg= tablets250 mcg1 ta
blet×1 mg1000 mcg×0.125 mg= tablets
, Step 3: Cancel units (mcg and mg) and solve.
1 tablet×1000×0.125250=125250=0.5 tablets2501 tablet×1000×
0.125=250125=0.5 tablets
Medication Safety Note: Digoxin has a narrow therapeutic
index. A 0.5 tablet is a safe and practical dose. Always question
an order that requires cutting a tablet into more than two or
three pieces due to the risk of inaccurate dosing.
Question 3
Topic: Liquid Medications (Easy)
A patient is prescribed amoxicillin 500 mg PO every 8 hours. The
bottle of amoxicillin suspension is labeled 250 mg/5 mL. How
many teaspoons should the nurse instruct the patient to take
per dose?
A. 1 teaspoon
B. 2 teaspoons
C. 3 teaspoons
D. 4 teaspoons
Correct Answer: B. 2 teaspoons
Rationale:
Step 1: First, calculate the volume in mL required for the dose.
5 mL250 mg×500 mg=10 mL250 mg5 mL×500 mg=10 mL
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Topic: Basic Arithmetic & Unit Conversions (Easy)
The nurse is preparing to administer famotidine 20 mg PO. The
medication is available as famotidine 40 mg/5 mL. How many
mL will the nurse administer?
A. 1 mL
B. 2.5 mL
C. 5 mL
D. 10 mL
Correct Answer: B. 2.5 mL
Rationale:
Step 1: Identify the desired amount and the available
concentration. The order is for 20 mg. The supply is 40 mg per 5
mL.
Step 2: Set up the dimensional-analysis equation to solve for
mL.
5 mL40 mg×20 mg= mL40 mg5 mL×20 mg= mL
Step 3: Cancel the common unit (mg) and solve.
5 mL40×20=10040 mL=2.5 mL405 mL×20=40100 mL=2.5 mL
Medication Safety Note: Always double-check your calculation,
especially with high-alert medications like anticoagulants or
,insulin. If the calculated dose seems significantly different from
usual doses, re-evaluate the order and your math. Use a second
nurse to verify calculations for high-risk medications.
Question 2
Topic: Oral Dosage Calculations (Easy)
The healthcare provider orders digoxin 0.125 mg PO daily. The
pharmacy provides digoxin 250 mcg tablets. How many tablets
will the nurse administer?
A. 0.25 tablets
B. 0.5 tablets
C. 1 tablet
D. 2 tablets
Correct Answer: B. 0.5 tablets
Rationale:
Step 1: Convert the ordered dose to the same unit as the
available tablet. The order is 0.125 mg, and the tablet is 250
mcg. Convert mg to mcg: 1 mg = 1000 mcg. So, 0.125 mg = 125
mcg.
Step 2: Set up the dimensional-analysis equation.
1 tablet250 mcg×1000 mcg1 mg×0.125 mg= tablets250 mcg1 ta
blet×1 mg1000 mcg×0.125 mg= tablets
, Step 3: Cancel units (mcg and mg) and solve.
1 tablet×1000×0.125250=125250=0.5 tablets2501 tablet×1000×
0.125=250125=0.5 tablets
Medication Safety Note: Digoxin has a narrow therapeutic
index. A 0.5 tablet is a safe and practical dose. Always question
an order that requires cutting a tablet into more than two or
three pieces due to the risk of inaccurate dosing.
Question 3
Topic: Liquid Medications (Easy)
A patient is prescribed amoxicillin 500 mg PO every 8 hours. The
bottle of amoxicillin suspension is labeled 250 mg/5 mL. How
many teaspoons should the nurse instruct the patient to take
per dose?
A. 1 teaspoon
B. 2 teaspoons
C. 3 teaspoons
D. 4 teaspoons
Correct Answer: B. 2 teaspoons
Rationale:
Step 1: First, calculate the volume in mL required for the dose.
5 mL250 mg×500 mg=10 mL250 mg5 mL×500 mg=10 mL
