# Chapter 9. Math and Statistical Functions

Excel is packed with dozens of mathematical functions. Some of these functions are for specialist audiences, like engineers or statisticians, while others are so useful they can turn up in almost any civilian’s spreadsheet.

In this chapter, you’ll take a tour of two of the largest categories in Excel’s function library, namely the Math & Trig and Statistical functions. Rather than slog through each function one by one, this chapter covers the most useful functions in each category. It starts by looking at a bunch of functions that help round, add, and count numbers. Then it explains how to find averages, medians, and percentiles, which are helpful when you want to compare groups of data. Toward the end of the chapter, you’ll see some of the more specialized functions that showcase Excel’s skill with trigonometry and advanced statistics—great for math lovers, accounting jockeys, or political-polling wonks interested in double-checking statistical significance claims.

# Rounding Numbers

Most people don’t devote enough thought to rounding, the process by which you adjust fractional numbers so they’re less precise but more manageable. For example, rounding can transform the unwieldy number 1.984323125 to 2. Excel lets you round numbers two ways:

• Modify the number format of the cell. With this method, Excel rounds the displayed value, but doesn’t change the underlying value. The advantage to this approach is that you can use the value in other calculations ...

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