# How to Use Negative Numbers to Calculate in Excel

Microsoft Excel spreadsheets can handle inventory: what you have, what you had, what you sold and what you have left. You can input figures into a Microsoft Excel spreadsheet and subtract a number from what you originally had in inventory to determine what's left. You can use negative numbers to show the difference; for example with "15 - 10," this equation is actually "15 + (-10)."You can format the way negative numbers appear in your spreadsheet. Numbers can be formatted with a negative sign, with double parentheses, or by using the color red.

### Calculating Negative Numbers

#### Step 1

Enter a negative number into an Excel spreadsheet cell by using the minus sign (-) before the number. "-12" is an example of a negative number.

#### Step 2

Use the arithmetic operator, the minus sign (-), to subtract a number using a formula. An example is the formula, "=25-10" that will give a result of "15."

#### Step 3

Use a function to calculate negative and positive numbers. An example of this is "=sum(a1:a3)", where cell a1=10, cell a2=12 and cell a3=-25 will give a result of "-3."

#### Step 4

Use a function to transform a positive result into a negative result by applying the negative sign (-) to the function. An example of this is "=-sum(a1:a3)" using the established values for those cells will give a result of "3."

### Change Negative Number Formats

#### Step 1

Select a number or range of numbers to change the way Excel displays these numbers.

#### Step 2

Click the "Home" tab on the top menu and select the arrow in the "Number" section.

#### Step 3

Choose either the "Number" or the "Currency" category in the "Category:" list in the "Format Cells" window.

#### Step 4

Select the number of decimal places by either typing it in or selecting the up or down arrow in the "Format Cells" window.

#### Step 5

Choose the "Use 1000 Separator (,)" check box. Skip this if you are formatting currency.

#### Step 6

Choose the currency symbol by clicking the down arrow in the box next to "Symbol." Skip this if you are not formatting currency.

#### Step 7

Select the number format in the "Negative numbers:" box in the "Format Cells" window.

#### Step 8

Click the "OK" button.

### Tips & Warnings

- Negative times will be displayed as number symbols (####). You can adjust the way the number is displayed by using the TEXT function.