Quick answer

Subtracting a negative number means adding its positive opposite. Here is why the rule works and how to avoid sign errors.

Rewrite the operation

For any numbers a and b, a - (-b) = a + b. The first minus is subtraction; the second belongs to the negative number.

Try a number-line explanation

Starting at 3, subtracting -4 moves four units right, not left. You land on 7.

Separate signs with parentheses

Writing 6 - (-2) is easier to read than 6--2. Parentheses help prevent copying errors.

Worked examples

  • 3 - (-4) = 7
  • -5 - (-2) = -3
  • 8 - (-8) = 16

Common mistake to avoid

Do not change every minus sign into a plus. Only subtracting a negative becomes addition.

Practice questions

Try these without looking at the answers first. Explain your reasoning aloud or write each step.

  • Question: 7 - (-3) — Answer: 10
  • Question: -4 - (-9) — Answer: 5
  • Question: 2 - 6 — Answer: -4

What to learn next

Review the related lessons linked below, then practice independently. If you make an error, write down which rule you used and why it did not apply.

Explore FitGitt practice.