Excel formulas: The most popular functions and tools

Excel has over 475 formulas in its Functions Library, from simple mathematics to very complex statistical, logical, and engineering tasks such as IF statements (one of our perennial favorite stories); AND, OR, NOT functions; and COUNT, AVERAGE, and MIN/MAX.

The basic functions covered below are among the most popular formulas in Excel—the ones everyone should know. To help you learn, we’ve also provided a spreadsheet with all the formula examples we cover here.

1. TODAY / NOW

There are 24 Date and Time functions listed on the drop-down menu under Formulas > Date & Time: 11 Date formats, 10 Time formats, and as many user-defined custom formats you can create. The TODAY function reveals the current month, day, and year; while the NOW function reveals the current month, day, year, and time of day. This is a handy function if you’re one of those individuals who always forgets to date your work.

1. Enter the following formula in cell A1: =TODAY() and press Enter.

2. Next, type over that function in A1 with =NOW().

IMPORTANT NOTE: Why type over? In order for these two formulas to work properly, they must be entered in the Home cell, that is, A1, otherwise, they won’t update automatically when the spreadsheet recalculates. Press Shift-F9 to calculate/recalculate the active spreadsheet only, or press F9 for the entire workbook.

After you enter one of these functions in A1, you can then reformat the Date and Time or use the system default. The default format for the TODAY function is 8/29/18, and the default for NOW is 8/29/18 21:57. If these don’t work for you, change them.

3. Position your cursor on the Date or Time you want changed and choose Home > Format > Format Cells.

4. In the Format Cells dialog window, choose Date (or Time) from the Category panel under the Number tab.

5. Scroll through the list of Date/Time formats in the Type dialog pane and select the format that best fits your project.

2. SUM FUNCTIONS

Probably the most frequently used function in Excel (or any other spreadsheet program), =SUM does just that: It sums a column, row, or range of numbers—but it doesn’t just sum. It also subtracts, multiplies, divides, and uses any of the comparison operators to return a result of 1 (true) or 0 (false).

You can also get the same results just using the plus (+) sign in place of the function SUM. For example, both of these formulas produce the same answer: =SUM(J7*9) and =+(J7*9). In the spreadsheet graphic, notice that cells