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.
1.
-13 + -12
2.
23 + 14
3.
-7 + -6
4.
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.
5.
17 + (-4)
6.
–23 + 18
7.
–11 + 9
8.
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.
9.
-4 - 7
10.
12 - 19
11.
(-1/3) - (4/5)
12.
13 -(-6)
13.
8 -(-6) - 7 + 14
14.
-6 + (-15) + 9 -(-21)