Page 83 - Math Genius C3

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Mind Map
math Creative Thinking
MulTiPliCATiON

Multiplication by a 1-digit Number Multiplication by a 2-digit Number

Without regrouping With regrouping With 2-digit number:
With 2-digit number: With 2-digit number: Example: 42 × 15 = 630
Example: 32 × 3 = 96 Example: 28 × 3 = 84 With 3-digit number:
With 3-digit number: With 3-digit number: Example: 234 × 23 = 5382
Example: 432 × 2 = 864 Example: 245 × 4 = 980
Exploring multiplication

By expanding the bigger number
Properties of multiplication Example: 67 × 5
67 = 60 + 7
Order Property: 60 × 5 = 300 and 7 × 5 = 35
Example: 8 × 4 = 32 = 4 × 8 300 + 35 = 335
Multiplication by 1: Thus, 67 × 5 = 335
Example: 53 × 1 = 53
Multiplication by 0: Multiplying by 10 and 100
Example: 17 × 0 = 0
Multiplying by 10:
Example: 3 × 10 = 30
Estimating product Multiplying by tens other than 10
Example: 2 × 20 = 40
Estimated product of 73 × 26. Multiplying by 100
73 rounded off to the nearest 10 is 70. Example: 6 × 100 = 600
26 rounded off to the nearest 10 is 30. Multiplying by hundreds other than 100
Thus, the estimated product of 73 × 26 = 2100. Example: 12 × 300 = 3600

Critical Thinking
Mental Maths
Fill in the blanks to make the multiplication facts true.

1. 2.
3 × = 9 8 × = 72

× × × × ×

15 = × 5

= = = = =

300 45 × 90 = 80

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