Subtracting integers
Subtract integers by rewriting subtraction as adding the opposite.
Objective
Subtract integers by rewriting subtraction as adding the opposite.
What it means
Subtracting an integer is the same as adding its opposite: a - b = a + (-b).
Key terms
- Opposite
- A number with the same absolute value but reversed sign.
- Minuend/Subtrahend
- The number being subtracted from, and the number subtracted.
Rules to remember
- To subtract, add the opposite of the second number.
- Then apply the addition rules for integers.
Step by step
- 1RewriteChange a - b into a + (-b).
- 2AddUse integer addition rules to finish.
Common mistakes
- Forgetting to flip the sign of the second number.
- Double negative confusion: - (-b) becomes +b.
Tips
- Say 'add the opposite' out loud before computing.
- Two negatives in a row become a positive.