What the Math section covers
School testing-center guides (for example TSTC and Odessa College) list the same core: whole numbers, fractions, decimals, percents, converting among them, ratio and proportion, basic algebra, and 12-hour ↔ military time; TSTC also lists Roman numerals and measurement conversion. Some guides, such as Sandhills Community College's, describe the section as the math used for drug dosages and solutions. There is little advanced algebra, and the guides do not list graphs or charts (Odessa College's does list mean, median, and mode). See every topic on the HESI A2 Math page.
Conversions to know cold
| Household / US | Metric or equivalent |
|---|---|
| 1 teaspoon (tsp) | 5 mL |
| 1 tablespoon (tbsp) | 15 mL (3 tsp) |
| 1 fluid ounce (oz) | 30 mL (2 tbsp) |
| 1 cup | 8 oz (about 240 mL) |
| 1 kilogram (kg) | 2.2 pounds (lb) |
| 1 inch (in) | 2.54 cm |
| 1 gram (g) | 1,000 mg |
| 1 liter (L) | 1,000 mL |
Several household values are rounded (a fluid ounce is about 29.6 mL), which is why health-care math uses 30 mL. When a question states its own conversion, use that one. Temperature: °C = (°F − 32) × 5/9, and °F = °C × 9/5 + 32.
A patient drinks 6 ounces of juice. Using 1 ounce = 30 mL, how many milliliters did the patient drink?
Set it up as a proportion
Dosage and conversion word problems usually come down to one proportion. Put the known relationship on one side and the unknown on the other, with matching units in the same position, then cross-multiply. For example, if 2 tablets weigh 500 mg, 3 tablets weigh x: 2/500 = 3/x, so x = 750 mg. Estimate first (more tablets, more mg) so a flipped ratio stands out.
The coach below walks through conversion problems one step at a time, the same arithmetic the HESI Math section tests:
Fractions, decimals, and percents
To turn a fraction into a decimal, divide top by bottom. To turn a decimal into a percent, move the decimal two places right. Keep the common ones memorized: 1/8 = 0.125 = 12.5%, 1/4 = 25%, 1/3 ≈ 33.3%, 3/8 = 37.5%, 1/2 = 50%, 2/3 ≈ 66.7%, 3/4 = 75%.
Which percent is equal to 3/8?
Roman numerals
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. Add values that go from largest to smallest (VIII = 8). Subtract a smaller numeral placed before a larger one: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. A numeral repeats no more than three times in a row.
What is the value of the Roman numeral XIV?
Military time
Military (24-hour) time runs from 0000 (midnight) to 2359. From 1:00 a.m. to 12:59 p.m. the digits stay the same, with a leading zero when needed: 7:30 a.m. = 0730. The hour after midnight starts at 00: 12:30 a.m. = 0030. From 1:00 p.m. on, add 12: 1:00 p.m. = 1300, 9:15 p.m. = 2115. To go back, subtract 12 from 1300 and later. Noon is 1200; midnight is 0000.
A medication is due at 1545. What is this time on a 12-hour clock?
How to study Math
- Memorize the conversion table first; it unlocks the most questions for the least time.
- Write the setup before you touch the calculator, then estimate the answer.
- Practice under the clock: about 55 seconds per question on average.
- Practice some problems without a calculator too, in case your school switches it off.
- Log every miss as a rule (“flip °F to °C: subtract 32 first”) and redo it two days later.
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Common questions
What math is on the HESI A2?
Arithmetic for health care: whole numbers, fractions, decimals, percents, ratios and proportions, household and metric conversions, temperature, Roman numerals, military time, and basic algebra word problems.
Can you use a calculator on the HESI A2?
Usually there is an on-screen calculator in the Math section, but Elsevier lets each school switch it off, and testing centers do not allow personal calculators or phones. Check your testing center’s rules and practice both ways.
How many math questions are on the HESI A2?
Usually 55 (50 scored plus 5 unscored pilot questions) in about 50 minutes. Your testing center may set a different time.
What conversions should I memorize for the HESI A2?
Common ones: 1 oz = 30 mL, 1 tsp = 5 mL, 1 tbsp = 15 mL, 1 cup = 8 oz, 1 kg = 2.2 lb, 1 in = 2.54 cm, 1 g = 1,000 mg, and 1 L = 1,000 mL. Some conversions are approximations, so use the value the question gives when it gives one.