Glossary
numerator
The numerator is the top number of a fraction: how many of the equal parts named by the denominator are being counted.
The numerator is the number above the line in a fraction, and it counts parts: in 3/4 it is the three, meaning three of the four equal pieces the whole was cut into. The bottom number, the denominator, names what is being counted, so the pair only makes sense together — swapping them changes the fraction's meaning and usually its size. The numerator is the number that behaves like a whole number in most operations in a way students find surprising: adding fractions requires the denominators to match and the numerators to be added, while multiplying fractions multiplies numerators and denominators straight across, with no common denominator needed. In a word problem, the numerator answers how much of it, the denominator out of what — and getting those two the right way round is the whole of many questions.
Taught in
Related terms
- denominator — The denominator is the bottom number of a fraction: how many equal parts the whole is divided into, and therefore the size of each part.
- mixed number — A mixed number combines a whole number and a proper fraction, such as 1 1/2, and is converted to an improper fraction before multiplying or dividing.
- least common denominator — The least common denominator is the smallest number that both denominators divide into evenly, and it is the shared bottom number used to add or subtract fractions.
Source: The math guides in this course (ratio and proportion, measurement and conversion, dosage calculation): every definition and worked value above was written for this course, because arithmetic and unit conversion are not a publisher's prose, and each guide shows the method worked. Elsevier's own HESI A2 page, which names math among the areas the exam covers, is the exam-side source. (Elsevier HESI A2 page accessed 2026-10-23; definitions written 2026-10-27)