Review the basic of subtracting negative numbers and try some practice problems.

Subtracting negative numbers

Subtracting a number is the same as adding the opposite of the number.
Let's look at two examples:
minus, 5, start color goldD, minus, 7, end color goldD, equals, minus, 5, start color goldD, plus, left parenthesis, minus, 7, right parenthesis, end color goldD
10, start color goldD, minus, left parenthesis, minus, 3, right parenthesis, end color goldD, equals, 10, start color goldD, plus, 3, end color goldD
Note: In both examples, we change subtraction to addition and changed the sign of the second number to the opposite sign.
Want to know why this works? Check out this video.
Once we have an addition problem, we can solve.

Example 1: negative minus negative

Lets subtract minus, 5, minus, left parenthesis, minus, 6, right parenthesis.
Step 1: Rewrite as an addition problem
minus, 5, start color goldD, minus, left parenthesis, minus, 6, right parenthesis, end color goldD, equals, minus, 5, start color goldD, plus, 6, end color goldD
Step 2: Start at the first number in the addition problem, in this case minus, 5:
Step 3: Move 6 places to the right. We move 6 to the right because adding positive 6 increases our number by 6.
minus, 5, plus, 6 takes us to 1 on the number line.
minus, 5, minus, left parenthesis, minus, 6, right parenthesis, equals, 1

Example 2: negative minus positive

Lets subtract minus, 4, minus, 7.
Step 1: Rewrite as an addition problem
minus, 4, start color goldD, minus, 7, end color goldD, equals, minus, 4, start color goldD, plus, left parenthesis, minus, 7, right parenthesis, end color goldD
Step 2: Start at the first number in the addition problem, in this case minus, 4:
Step 3: Move 7 places to the left. We move 7 to the left because adding negative 7 decreases our number by 7.
minus, 4, plus, left parenthesis, minus, 7, right parenthesis takes us to minus, 11 on the number line.
minus, 4, minus, 7, equals, minus, 11
Want to learn more about subtracting negative numbers? Check out this video.

Practice

Problem 1
Subtract.
minus, 8, minus, left parenthesis, minus, 2, right parenthesis, equals
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, p, i or 2, slash, 3, space, p, i

Want to try some more subtracting negative numbers problems? Check out this exercise.