Add and subtract integers

Key notes:

  • When you add positive numbers, the result is positive.
    • 5+8= 13
  • When you add negative numbers, the result is negative.
    • -10 + -20 =-30
  • When you add a positive number and a negative number:
    • If the positive number has a bigger magnitude, the result is positive. Ex: 10 + -5 =5
    • If the negative number has a bigger magnitude, the result is negative. Ex: 5 + -10 =-5
  • Adding a negative is the same as subtracting a positive.
    • You can add numbers in either order.
    • -3 + 10 = 10 + -3
  • Subtracting a negative is the same as adding a positive.
  • Instead of subtracting a number, you can add its opposite.
    • You can add numbers in either order.
    • -1 − (-4) = -1 + 4

Learn with an example

3 − 7 =

Since 7 is bigger than 3, the answer will be negative.

First, solve an easier problem:

7 − 3 = 4

Remember that the answer to the problem you’re solving will be negative:

3 − 7 = -4

-9 + 3 =

Switch the order of the numbers:

–9 + 3 = 3 + –9

Now change the negative sign to a subtraction sign:

3 + –9 = 3 − 9

Since 9 is bigger than 3, the answer will be negative.

First solve an easier problem:

9 − 3 = 6

Remember that the answer to the problem you’re solving will be negative:

3 − 9 = –6

So:

–9 + 3 = –6

-8+9=

Switch the order of the numbers:

–8 + 9 = 9 + –8

Now change the negative sign to a subtraction sign:

9 + –8 = 9 − 8

Subtract:

9 − 8 = 1

So:

–8 + 9 = 1

Let’s practice!🖊️