# Formulas You’ll Need to Know for Mathematics Questions on the HESI Test

## Why do nurses have to know math?

That’s the question you’re probably asking yourself as you’re preparing for the HESI Mathematics test. Well, math is a skill you’ll need for keeping records of your patients, understanding trends, and organizing information. That’s why the admittance test for nurses includes math.

But don’t worry, we’re here to help you. In the following chart, you’ll find easy-to-remember formulas that will be useful to you during the HESI Mathematics test. You’ll have access to a basic calculator during the test, but not to any other resources, so make sure you learn these formulas. A good way to do that is to use them for our free practice questions and flashcards.

$\begin{array}{|c|c|c|c|} \hline \textbf{Category} & \textbf{Formula} & \textbf{Symbols} & \textbf{Comment} \\ \hline \text{Fractions} & \dfrac{a}{b} +\dfrac{c}{d} = \dfrac{(a\cdot d) + (c\cdot b)}{b\cdot d} & a,b,c,d = \text{any real number} & \text{simplify the fraction }\\ & & &\text{(if possible) } \\ \hline \text{Fractions} & \dfrac{a}{b} \cdot \dfrac{c}{d} = \dfrac{a\cdot c}{b\cdot d} & a,b,c,d = \text{any real number} & \text{simplify the fraction }\\ & & &\text{(if possible) } \\ \hline \text{Fractions} & \dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a\cdot d}{b\cdot c} & a,b,c,d = \text{any real number} & \text{simplify the fraction }\\ & & &\text{(if possible) } \\ \hline \text{Fractions} & a\frac{b}{c} = \dfrac{a\cdot c + b}{c} & a,b,c = \text{any real number} & \text{simplify the fraction }\\ & & &\text{(if possible) } \\ \hline \text{Percents} & a \cdot b \% = a \cdot \frac{b}{100} & a = \text{any real number} & \text{simplify} \\ & & b \% = \text{any percent} & \text{(if possible)} \\ \hline & x + a = b \rightarrow x = b-a & & \\ & x - a = b \rightarrow x = b+a & & \\ & x \cdot a = b \rightarrow x = b \div a & a, b = \text{constants} & \\ \text{Algebra} & x \div a = b \rightarrow x = b \cdot a & x = \text{variable} & \\ & x^a = b \rightarrow x = \sqrt[a]{b} & & \\ & \sqrt[a]{x} = b \rightarrow x = b^a & & \\ & a^x = b \rightarrow x = \dfrac{\log b}{\log a} & & \\ \hline \end{array}$