Free HESI A2 study guide
HESI A2 Math is applied arithmetic rather than algebra for its own sake. Almost every question is framed the way a nurse meets it, which is why ratios, proportions and conversions carry most of the section.
Last updated August 2026
HESI question counts and timings are set by your nursing programme rather than published centrally, so there are no official per-subject figures to show here. Confirm which subjects you sit before planning around any.
The same value written three ways. A fraction is a division waiting to happen, a decimal is that division carried out, and a percentage is the decimal per hundred. Converting between them quickly is the single most reusable skill in this section, because dosage and concentration questions move between the three forms without warning.
Learn the common equivalents by heart: 1/4 is 0.25 and 25%, 1/3 is about 0.333 and 33.3%, 1/8 is 0.125 and 12.5%.
Factors divide into a number exactly; multiples are what you get by multiplying it. You need them to simplify fractions to their lowest terms and to find a common denominator before adding or subtracting, both of which appear inside longer questions rather than on their own.
To add fractions, find the least common multiple of the denominators. To simplify one, find the greatest common factor of the top and bottom.
Finding an unknown value by doing the same thing to both sides until the unknown stands alone. On the A2 this is nearly always one unknown in a single step or two, and it is usually dressed as a word problem rather than presented as algebra.
Write the equation before you calculate anything. Most lost marks here come from starting the arithmetic before deciding what is actually being asked.
Measurement conversion, ratio and proportion, military time, Roman numerals and basic statistics. These are grouped because they share a shape: real information given in one unit or format, and an answer required in another. Ratio and proportion is the workhorse, since it is how nearly every dosage calculation is set up.
Memorise 1 kg = 2.2 lb, 1 inch = 2.54 cm, 1 tsp = 5 mL and 1 oz is roughly 30 mL, in both directions.
Build a practice set from this section alone and read the rationale on everything you miss.
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