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Integers can be represented on the number line. On a number line,

• the positive numbers are to the right of zero and the negative numbers are to the left of zero.
• A number on the right is greater than a number on the left.
• A number on the left is less than a number on the right.

To add integers using the number line, always start at zero and move units to the right if the number is positive and units to the left if the number is negative.

Example #1: 2 + 4 = 6

Since the first addend is positive 2, move 2 units to the right from zero, and from 2, move 4 units to the right again until the mark 6 is reached.

Example #2: (-1) + (- 4) = - 5

Since the first addend is negative 1, move 1 unit to the left from zero, and from - 1 move 4 units to the left again until the mark - 5 is reached.

Example #3: (-5) + 8 = 3

Since the first addend is negative 5, move 5 units to the left from zero, and from -5 move 8 units to the right (since 8 is positive) until the mark 3 is reached.

## Things to Remember:

1. The sum of two positive integers is positive.

2. The sum of two negative integers is negative.

3. The sum of a positive and a negative integer is the difference between their absolute values. The sign of the sum follows the sign of the number with the greater absolute value.