This unit demonstrates some math fundamentals necessary to perform various calculations in the lab. The metric (SI) measurement system is described and practical instruction is given on the conversion to English units and vice versa. Exponential numbers are explained, and trainees are shown how to perform arithmetic operations with them. Also, the rules for significant figures and rounding are described. Converting between fractions, decimals, and percents is demonstrated; and finally, ratios and proportions are explained and examples of their practical use are shown.