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Chapter 1 · Numbers · page 2 of 68

Subtracting a negative

levelPre-algebra
standard7.NS.A.1
practiceInteger operations

Subtracting a number means adding its opposite. So subtracting a negative is adding a positive. The two minus signs become a plus.

How to use it

  1. Rewrite the subtraction as adding the opposite.
  2. Then add using the signed-number rules.

Example

8−(−3)=8+3=118 - (-3) = 8 + 3 = 11
−4−(−9)=−4+9=5-4 - (-9) = -4 + 9 = 5
−4−9=−4+(−9)=−13-4 - 9 = -4 + (-9) = -13

Where it goes wrong

  • Treating 8 − (−3) as 8 − 3. The minus in front of the parentheses flips the sign inside.
  • Reversing the order: 4 − 9 is not 9 − 4.

Related

Adding signed numbersA negative outside parentheses
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