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Med math · 5 free problems

Unit conversion practice: grams, milligrams, micrograms, liters

Every other med math problem starts here. Write the conversion factor as a fraction, place the unit you want to remove in the denominator, and check that the number moves in the direction you expect.

Fictional labels. Round as each question says. How to round

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Unit conversions: work through the set

Question 1 of 5

Grams to milligrams

A practice label lists 0.48 g of a fictional medication. How many milligrams is that? Use 1 g = 1,000 mg. Give the exact answer in mg; no rounding is needed.

Worked solution and answer

Answer: 480 mg.

0.48 g × (1,000 mg / 1 g) = 480 mg. The grams cancel, leaving milligrams. The number increases because a milligram is a smaller unit than a gram.

Check: 480 mg ÷ 1,000 mg/g = 0.48 g.

If you got 0.00048: You divided by 1,000. Arrange the conversion so grams cancel and mg remains.

Question 2 of 5

Micrograms to milligrams

A practice label lists 650 mcg of a fictional medication. Express that amount in mg. Use 1 mg = 1,000 mcg. Give the exact answer; no rounding is needed.

Worked solution and answer

Answer: 0.65 mg.

650 mcg × (1 mg / 1,000 mcg) = 0.65 mg. Micrograms cancel, leaving mg.

Check: 0.65 mg × 1,000 mcg/mg = 650 mcg.

If you got 650,000: You multiplied by 1,000. Moving from the smaller mcg unit to the larger mg unit makes the number smaller.

Question 3 of 5

Milligrams to micrograms

A practice label lists 0.25 mg of a fictional medication. How many micrograms is that? Use 1 mg = 1,000 mcg. Give the exact answer in mcg; no rounding is needed.

Worked solution and answer

Answer: 250 mcg.

0.25 mg × (1,000 mcg / 1 mg) = 250 mcg. The mg units cancel. The number grows because a microgram is the smaller unit.

Check: 250 mcg ÷ 1,000 mcg/mg = 0.25 mg.

If you got 0.00025: You divided by 1,000. Going from a larger unit to a smaller one, the number of units gets bigger.

Question 4 of 5

Liters to milliliters

An infusion-math exercise lists a bag volume of 1.75 L. Express that volume in mL. Use 1 L = 1,000 mL. Give the exact answer; no rounding is needed.

Worked solution and answer

Answer: 1,750 mL.

1.75 L × (1,000 mL / 1 L) = 1,750 mL. Liters cancel.

Check: 1,750 mL ÷ 1,000 mL/L = 1.75 L.

If you got 17.5: You moved the decimal one place. A liter holds 1,000 mL, so move it three places.

Question 5 of 5

Milliliters to liters

A practice record lists an intake of 350 mL. Express that volume in L. Use 1 L = 1,000 mL. Give the exact answer in L; write a zero before the decimal point.

Worked solution and answer

Answer: 0.35 L.

350 mL × (1 L / 1,000 mL) = 0.35 L. The mL units cancel.

Check: 0.35 L × 1,000 mL/L = 350 mL.

If you got 3.5: You moved the decimal two places instead of three. Divide by 1,000, not 100.

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