Automatically calculate mathematical formulas by entering your numeric values into a spreadsheet. In Microsoft Excel, you can use the equals symbol to indicate the start of a formula in a cell of your worksheet. Some of the most basic Excel math formulas include addition, subtraction, multiplication and division. Apply the same formula pattern to adjacent cells to avoid entering repetitive formulas in worksheet. Additional formulas can be accessed using the commands in the Function Library group of the Formulas ribbon.

## Basic Math Formulas

Entering a formula into Excel enables you to calculate values using common math. Formulas must start with an equals sign before the equation. For example, if you enter "=1+2" without the quotes, into an empty cell in a worksheet and then press "Enter," the cell's value changes to reflect the answer to your formula -- 3. You can use the common symbols for your formulas: enter "+" to add, "-" to subtract, "*" to multiply and "/" to divide. You can also use "SQRT" to calculate the square route and "%" for percentages.

## SUM Function

You can use the SUM function to calculate the sum of the cells in a column or row. Enter "=SUM(n,n)" without the quotes, replacing "n" with the numbers you wish to add. For example, "=SUM(3,4)" produces the number 7 as the sum of 3 and 4. To calculate the sum of a row or column, click a cell that is directly below or to the right of the values you wish to include in your calculation. Click "AutoSum" in the Editing group of the Home ribbon and then press "Enter" to display the answer for the SUM function.

## Cell References

Reference another cell whenever you calculate formulas so that when the originating cell's numeric value is updated, your formula's result will reflect the adjusted value. For example, if you want to add cell A2 with cell B3, enter "=A2+A3" and then press "Enter" to add the two cells together. You can also specify a range of cells using the colon symbol. For example, "=SUM(A2:A6)" is a formula that calculates the sum of cells A2 through A6.

## Filling Formulas

Cell references help you find the numeric values for formulas you use often in your worksheet. You can fill your formula into cells that are next to the cell containing your original formula. Click on the fill handle, which resembles a small black box in the lower right corner of the cell, then drag the fill handle into the adjacent cells you wish to apply your formula to and release the handle. Select the cell to view the formula in the formula bar at the top of your worksheet.