In addition to entering formulas that perform basic math — such as adding, subtracting, multiplying, and dividing — you can use a vast library of builtin worksheet functions in Microsoft Excel to do much more.
You can use these functions to return information, such as:

Getting the current date.

Finding the number of characters in a cell.

Manipulating text; for example, converting "hello" to "Hello" or even "HELLO."

Calculating a loan payment.

Testing the contents of two cells to see which is larger or if they are identical.
How?

Start typing in a cell


Choose a function and fill in its arguments
Enter one or more arguments after the opening parenthesis, if necessary. An argument is a piece of information that the function uses. Excel shows you what type of information you should enter as an argument. Sometimes it's a number, sometimes it's text, and sometimes it's a reference to another cell. For example, the ABS function requires one number as its argument. The UPPER function (which converts any lowercase text to uppercase text) requires one string of text as its argument. The PI function requires no arguments, because it simply returns the value of pi (3.14159...).


Complete the formula and see the results
Excel adds the closing parenthesis for you, and the cell shows the result of the function that you used in the formula. Select the cell and look at the formula bar to view the formula.

Next steps

Watch a video to see how to use functions: Video: Use functions in formulas

Try creating formulas that use nested functions; that is, a formula that uses one function and then uses the result of that in another function.

Try using some functions that you've never used before and see if they return the values you expect.