 # Adding Integers and Subtracting Integers

In these lessons, we will look at adding integers and subtracting integers using the number line and using rules.

Related Topics:
Integer Worksheets
Integer Games
More Lessons on Integers

### Using the Number Line

When we add, we move right on the number line.

When we subtract, we move left on the number line

Example:

To evaluate –3 + 2 , we start at –3 and move 2 places to the right ### Subtracting integers

To evaluate –3 – 2 , we start at –3 and move 2 places to the left How to add integers and subtract integers using the number line? How to think about adding and subtracting integers on a number line?

#### Using Rules to Add Integers

Using the number line to add or subtract integers may be quite tedious. A quicker method would be to use the following rules:

Rule 1 :

The sum of two or more positive integers is a positive integer.
The sum of two or more negative integers is a negative integer.

Example:

(+7) + (+ 4) = + 11
(– 8) + (– 9) = – 17

Rule 2 :

To find the sum of a positive and a negative integer:
Subtract the two numbers (ignore the signs) and then keep the sign of the larger integer.

(– 9) + (+ 7) = – 2
(– 3) + (+ 5) = + 2

Rule 3 :

The sum of an integer and its opposite is equal to zero

(– 9) + (+ 9) = 0
(– 3) + (+ 3) = 0

How to use the rules to add integers?

#### Using Rules to Subtract Integers

To subtract integers, we can rewrite the subtraction problem as an addition problem. Instead of subtracting, we add the opposite.

• Subtracting a positive is the same as adding a negative.

3 − (4) = 3 + (−4)

• Subtracting a negative is the same as adding a positive.

3 − (− 4) = 3 + 4

Basic rules for subtracting integers and provides examples
Each subtraction problem is rewritten as an addition problem. Subtracting Integers using Rules

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