Rule 1:
Adding Like Signs
When adding like signs, add the absolute value of all the numbers and attach the common sign.
Ex: 5 + 4 = 9 The common sign is positive and the total of the absolute values of 5 and 4 is 9.
Ex: -5 + (-4) = -9 The common sign is negative and the total of the absolute values is -9.
Rule 2:
Adding Unlike Signs
When adding unlike signs, subtract the smaller absolute value from the larger absolute value and attach the sign of the
larger number.
Ex: -6 + 3 = -3 The sign of the larger number is negative. Write that down immediately. Then, add subtract the smaller absolute value from the larger.
Ex: 6 + (-3) = 3 The sign of the larger number is positive. Write that down immediately. Then, add subtract the smaller absolute value from the larger.
Rule 3:
Subtraction
When subtracting, add the opposite!
3 - (-4) = 3 + 4 = 7 (Rule 1)
-3 - (-4) = -3 + 4 = 1 (Rule 2)
