Assignment - 07-Multiplying and Dividing Integers
This is something we should only need to spend one day on. Now, I hear what you’re thinking. ”You spent three or four days on adding and subtracting, how is it you’re only going to spend one day on multiplying and dividing?” Simple. It’s that easy. The students have been multiplying and dividing since about third grade. They know that 3×3=9, or more difficult, they could figure out that 12×15=180. With division, they know that 12÷6=2, and again more difficult, they should be able to do the long division for 126÷3=42. Multiplying and dividing with positive and negative numbers adds two simple rules into the mix.
Rule 1: If the signs are the same, whether positive or negative, than the answer is positive.
- 3 x 4 = 12 (positive times positive equals positive)
- 15 ÷ 3 = 5 (positive divided by positive equals positive)
- -2 x -6 = 12 (negative times negative equals positive)
- -32 ÷ -8 = 4 (negative divided by negative equals positive)
Rule 2: If the signs are different, than the answer is always negative.
- 5 x -6 = 30 (positive times negative equals negative)
- 60 ÷ -12 = -5 (positive divided by negative equals negative)
- -12 x 10 = -120 (negative times positive equals negative)
- -56 ÷ 7 = -8 (negative divided by positive equals negative)