Vocabulary

Integer – whole numbers and their opposites {…, -3, -2, -1, 0, 1, 2, 3, …}

Negative integer – any integer less than zero. 

Positive integer – any integer greater than zero.

Concept

Add and subtract integers

Rules

When subtracting numbers that are the same sign, both positive or both negative: 

1. Add the numbers together.
2. Use the original sign, either positive or negative.
3. Apply units if given

When subtracting numbers that are different signs, one positive and one negative:  

1. Subtract the numbers.
2. Take the sign of the number with the larger absolute value.

Example

Evaluate.

(-3) - 5

Solution

(-3) - 5 means starting at (-3) on the number line, and moving left 5 units. That results in (-8). When combining like terms with the same sign, simply add the terms together, and use the sign from the original numbers. 3 + 5 = 8, both numbers were negative, therefore -8.

Pre-requisite Skills

Adding Integers (7.3.2)

Subtracting Integers (7.3.3)