Subtracting Rational Numbers

2.3

Subtracting Rational Numbers

When subtracting rational numbers we follow the rules for subtracting integers.

KEEP the sign of the first number the same
CHANGE subtraction to addition
CHANGE the sign of the second number to the opposite, positive becomes negative, negative becomes positive.

Subtracting Fractions

After using keep change change, find a common denominator and look at the signs of your numbers.

If signs are the same
  • Add
  • Keep the sign


If the signs are different

  • Subtract the smaller number from the larger number
  • The number with the larger absolute value determines the sign of your answer.

Subtracting Decimals

After using keep, change, change look at the signs of your numbers.

If the signs are the same
  • Add
  • Keep the sign

If the signs are different

  • Subtract the smaller number from the larger number
  • The number with the larger absolute value determines the sign of your answer.



Be sure to LINE UP DECIMALS!

Subtracting Rational #s w/negative decimals