1. Multiplication of Integers

2. What Does it Mean to Multiply?
_____________ groups of _______________
Number of groups
Multiplier
Amount in each group
Multiplicand or “given number”

3. Two-Color Counters
Positive Integers
Negative Integers

4. What Does it Mean to Multiply by a Negative 1?
-1 × 5 = -5
-1 × -5 = 5
-1 × n = -n
When multiplying by -1, take the opposite of the multiplicand, or given number.

5. Positive × Positive 3 x 5
Interpretation: 3 groups of 5
Start with: 5
Action: 3 groups

6. Positive × Negative 3 x -5 Interpretation: 3 groups of negative 5
Start with: -5
Action: 3 groups

7. - (3 x 5) Negative × Positive -3 x 5
Interpretation: the opposite of 3 groups of 5
Start with: 5
1st Action: 3 groups
2nd Action: Take the opposite
- (3 x 5)

8. Negative × Negative -3 x -5
Interpretation: the opposite of 3 groups of negative 5
Start with: -5
1st Action: 3 groups
2nd Action: Take the opposite of 3 groups of -5
- (3 x -5)