Considered sign numbers, integers are both positive and negative. Whether you are dividing, subtracting, adding or multiplying, integers are always whole numbers, such as 14 or 11 but not 1.5. Fractions, decimals and percentages are all considered rational numbers, but since integers also have whole numbers, they are also considered rational and integers. When you are using a calculator to solve for integers, you will use the "-" sign found on all scientific calculators to solve for negative integers.

Determine if you are adding, subtracting, dividing or multiplying a positive or negative integer.

Locate the "-" sign on your calculator. Most scientific and graphing calculators will have the "-" sign located at the bottom next to the equal sign. Enter the negative sign if you are using a negative integer. If you are using a positive integer, do not enter the negative sign.

Enter a number followed by the negative sign. For example, "-9."

Enter a mathematical sign, such as addition, subtraction or multiplication, after the number you entered in Step 1. For example, you would now have "-9+."

Enter the final integer. For example, "-9+-9" followed by the equal sign. Your calculator will show the answer is -18.