Addition and Subtraction

Addition:

Same sign:

The sum of two positive integers is positive

The sum of two negative integers is negative

Different signs:

Find the absolute value of each integer

Subtract the smaller integer from the larger integer

Use the original sign of the integer with the larger absolute value

Using a number line:

This method is practical for small numbers. Start at 0 and count to the first number in the addition problem. Make a dot. Then start at this dot and count the number of spaces of the second number. For positive numbers, count to the right. For negative numbers, count to the left.

Using Algebra Chips:

Write out positive and negative signs for each number you have. Cancel out one positive sign with one negative sign. Count up the remaining signs (all positive or all negative) for your answer.

Subtraction:

To subtract an integer, add its opposite. Then follow the rules above.

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