AlgebraLab

Algebra I Recipe: Addition and Subtraction of Real Numbers

By G Redden

A. Adding Real Numbers with Like Signs
  1. Add their absolute values.
  2. Answer will have the like sign.
  3. "Slang" – add the numbers, keep the sign.

-13 + -12

23 + 14

-7 + -6

8 + 13

B. Adding Real Numbers with Unlike Signs
  1. Subtract the smaller absolute value from the larger one.
  2. Answer will have the same sign as the larger number.
  3. "Slang" – find the difference between the numbers and take the sign of the larger number for the answer.

17 + (-4)

–23 + 18

–11 + 9

8 + -3

C. Subtracting Real Numbers
  1. Change subtraction to addition.
  2. Change the number being subtracted to its opposite.
  3. Go back to the addition steps.
  4. "Slang" – add the opposite
  5. x - y is the same as x + (-y) AND x + (-y) is the same as x - y.

-4 - 7

12 - 19

(-1/3) - (4/5)

13 -(-6)

8 -(-6) - 7 + 14

-6 + (-15) + 9 -(-21)

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