# Standard Deviation on the GMAT

The formula for standard deviation is not pretty. Fortunately, you don’t need to memorize it. Instead, you need to know what standard deviation measures.

In this first video, we examine how to calculate range, and we take a close look at the formal and informal definitions of standard deviation.

In the second video, we learn how to calculate variance and how to work with units of standard deviation

To help reinforce the concepts you learned in the video, try answering the following practice question: