CRNA School Interview Math Questions: 8 to Work Out Loud

CRNA school interview math questions usually test whether you keep the units straight while you talk through your work. Start with the unit the question asks for, cancel units on paper, and check whether the answer is the right size. These eight examples give you a way to practice that out loud (yes, out loud, and talking to yourself in the car counts).

Updated October 2026.

You don’t need to race the person asking. A correct setup someone else follows step by step beats a number you guessed in three seconds, every time. One KEY reminder before we start: these are practice calculations only, so please don’t treat them as medication preparation instructions. In clinical care, you check the actual label, the order, and your local process.

How should you answer CRNA school interview math questions?

Say what you’re solving for before you touch a single number. Then write the conversion or concentration so the units you don’t want cancel out. Don’t drop the units halfway through. If your answer comes out 1,000 times bigger than you expected, that’s your cue to stop and redo it.

The two anchors are 1 mg = 1,000 mcg and 1 g = 1,000 mg. Both come straight from the milli- and micro- prefixes in the NIST metric system reference. And say “micrograms” out loud when you answer, because “mcg” is SO easy to misread when you’re nervous.

A spoken pattern I like: “I need micrograms. I have milligrams. I multiply by 1,000 micrograms per milligram, so milligrams cancel.” The same pattern works for concentrations and weight-based calculations too.

If the interviewer hands you a blank sheet, use it. Write the requested unit at the far right, then work backward until the units in the problem connect to it. For example, a question asking for mcg when the label gives mg/mL and the volume is in mL needs two moves: multiply by mL to get mg, then convert mg to mcg. Doing that setup first keeps you from answering a different question correctly. The interview question hub is a good place to mix a math prompt into a broader practice session.

How would you work these eight interview math questions?

Try each one before you read the line below it. Better yet, put your phone down and explain it as if an interviewer caught you right after a 12-hour shift (bonus points if you’re still in scrubs).

1. How many micrograms are in 0.75 mg?

0.75 mg × (1,000 mcg / 1 mg) = 750 mcg

The milligrams cancel. Anything under 1 mg should be under 1,000 mcg, so 750 passes the size check.

Say it in the room: “The conversion is 1,000 micrograms per milligram. Point seven five times 1,000 is 750 micrograms. Since I started with less than a milligram, my answer should be less than 1,000 micrograms.” That last sentence shows you checked your own work.

2. How many milligrams are in 250 mcg?

250 mcg × (1 mg / 1,000 mcg) = 0.25 mg

Going from micrograms to milligrams, the number’s going to get smaller. Got 250,000 mg? The conversion went the wrong way.

3. A vial is labeled 50 mcg/mL. How much drug is in 4 mL?

50 mcg/mL × 4 mL = 200 mcg

The milliliters cancel, and you’re left with a mass. Which is exactly what the question asked for.

If they change the question: “How many mL contain 200 mcg?” Reverse the setup: 200 mcg ÷ 50 mcg/mL = 4 mL. Don’t memorize “multiply for this drug.” Decide whether they asked for mass or volume, then let the units tell you which operation works.

4. A solution contains 120 mg in 12 mL. What is its concentration?

120 mg / 12 mL = 10 mg/mL

Say the unit with your answer. “Ten” by itself might mean a dose, a volume, or a concentration, and your interviewer shouldn’t have to guess which one you meant.

5. How many milligrams per milliliter are in a 1% solution?

For a percent weight/volume solution, 1% means 1 g in 100 mL. Convert grams to milligrams, then divide by the volume:

(1,000 mg / 100 mL) = 10 mg/mL

Still, check the product label instead of assuming every medication uses the same percent convention. For example, DailyMed lists 1% lidocaine injection as 10 mg/mL.

Follow-up worth practicing: “What does 0.5% mean if the label uses weight per volume?” It would be 0.5 g per 100 mL, or 500 mg per 100 mL, which is 5 mg/mL. Say the assumption about weight per volume before doing the math. If the interviewer gives you a real product label, use its printed concentration instead of applying a memorized percent rule.

6. How much drug is in 3 mL of a 1% solution labeled 10 mg/mL?

10 mg/mL × 3 mL = 30 mg

You’ll use the labeled mg/mL value from the last question. If you jump straight from “1%” to “3 mL,” you’ve got no unit bridge to get you to mass.

7. A practice problem gives 0.2 mcg/kg/min for a 75-kg patient. How many micrograms is that over 10 minutes?

0.2 mcg/kg/min × 75 kg × 10 min = 150 mcg

Kilograms and minutes both cancel. Notice this one’s asking for a total amount (an infusion pump setting is a whole different question). Real dosing decisions and pump programming require independent checks.

8. A syringe label says 1 mg in 10 mL. What is the concentration in mcg/mL?

First find mg/mL: 1 mg / 10 mL = 0.1 mg/mL.

Then convert: 0.1 mg/mL × (1,000 mcg / 1 mg) = 100 mcg/mL.

The answer should land under 1,000 mcg/mL, because the syringe has only 1 mg spread across 10 mL.

Now reverse it aloud: “If I had 100 mcg/mL, how much is in 2 mL?” Answer: 100 mcg/mL × 2 mL = 200 mcg. If your answer comes out in mL, you have not answered how much drug is present. That kind of quick reverse question tells you whether you understand the concentration or only remember the first calculation.

What mistakes should you check for in medication math answers?

The common mistakes are unit errors: converting in the wrong direction, confusing drug amount with solution volume, and giving a bare number with no unit. The fix is to say what you need, show one line of units, and check the magnitude before you commit to the answer. An interviewer may interrupt with “Are you sure?” even when your arithmetic is right. Go back to the setup instead of changing the answer because of their tone.

Try this miniature drill. The question says, “A label reads 2 mg in 20 mL. What’s the concentration in mcg/mL?” Start with 2 mg ÷ 20 mL = 0.1 mg/mL; convert to 100 mcg/mL. Now imagine you accidentally said 100 mg/mL. The arithmetic looks familiar, but the unit makes the answer 1,000 times too large. Catch that before anyone else does. In practice, say, “Let me correct the unit. The answer is 100 micrograms per milliliter.” A calm correction is stronger than defending a number you know is wrong.

For a three-day practice block, work two conversions on day one, concentration and percent problems on day two, and mixed weight-and-time problems on day three. On each day, answer once on paper and once without looking down. If your setup fails, write the exact unit you lost. That gives you a useful study list instead of the vague note “review math.” The CRNA Club membership has guided interview prep if you want to put these drills into a larger plan; use your own unit sheet either way.

What should you do if you blank on a conversion?

First, breathe. Fear and excitement feel almost identical in your body (racing heart, sweaty palms, the whole thing), so tell yourself you’re excited instead of afraid. Then write “1 mg = 1,000 mcg” on the paper and build from there.

It’s completely fine to say, “I’m going to set up the units so I don’t reverse the conversion.” That’s a reasonable thing for a clinician to say. Inventing a number and acting sure? Much worse.

For your next practice round, mix up the question types. Five easy mg-to-mcg conversions in a row feel great, right up until someone switches to mg/mL on you. So work one conversion, one concentration, and one weight-and-time problem, then explain each one without peeking at your notes.

One last way to test yourself: hide the question and look only at the final unit. If it says mcg/mL, tell yourself what kind of number that is: a concentration. If it says mcg, it is an amount. If it says mL, it is a volume. Then reveal the question and see whether your answer has the same kind of unit the interviewer asked for. This catches errors that a calculator will happily preserve.

The CRNA Club’s interview question hub has the wider set of clinical and behavioral prompts. Want to hear yourself answer under time pressure? Try the free mock interview. Write down any setup you missed, and work that type again before you take another round. You got this.