Understanding Multiplication
Use the Base 4 blocks to find these products.
214 334
× 134 ×234
Find the following products in Alphabitia:
AB CD ×B0 ×DC
Find the following products in Base 8:
258 578
×138 ×648
Multiplication terms
1234
multiplier: 4multiplicand: 3product: 12factors: 4 and 3 are factors of 12multiple: 12 is a multiple of 4
12 is a multiple of 3
Multiplication Models• Repeated addition
• Area
• Cartesian product
3333
a1
a2
a3
Figure 3.13
Units
• For addition and subtraction3 hours plus 5 miles
• For multiplication
8 miles per hour for 5 hours:how many miles?8 mi • 5 hr = 40 mi
hr
MultiplicationProperties
• Identity
• Zero
• Commutative
• Associative
Multiplication
Properties continued:Distributive property--
combines multiplication and addition or subtraction
The area model and the standard multiplication algorithm
Figure 3.20
Figure 3.21
Figure 3.22
Expanded vs compacted
Expanded Compacted
Multiplication-the area model
• How could Jemea’s strategy be represented using the rectangular area model?
10 + 10 + 10 + 2
10
+
4
Understanding FOIL