Page 149 - New Medley 3 Semester 1

EXERCISE 4.4

Fill in the blanks.

1. 2 × 10 = 2. 5 × 10 = 3. 18 × 10 =

4. 24 × 10 = 5. 231 × 10 = 6. 462 × 10 =

7. 5 × 100 = 8. 6 × 100 = 9. 72 × 100 =

10. 43 × 100 = 11. 5 × 1000 = 12. 6 × 1000 =

Multiplying by 20, 30, …, 90

Example 5: Multiply 3 by 20.

Solution: 3 × 20 = 3 × 2 tens = 6 tens = 60

Multiply 3 by 2 and put a zero on the right of the product.

Example 6: Multiply 18 by 30.

Solution: 18 × 30 = 18 × 3 tens = 54 tens = 540

Multiply 18 by 3 and put a zero on the right of the product.

EXERCISE 4.5

Multiply:

1. 3 × 20 = 2. 6 × 30 = 3. 8 × 40 =

4. 3 × 50 = 5. 4 × 60 = 6. 5 × 70 =

7. 6 × 80 = 8. 4 × 90 = 9. 42 × 20 =

10. 73 × 30 = 11. 24 × 40 = 12. 13 × 50 =

13. 35 × 60 = 14. 73 × 70 = 15. 15 × 80 =

Multiplying Two Multiples of 10

Example 7: Multiply 70 by 80.

Solution: 70 × 80 = 7 tens × 8 tens = 5600

(multiply 7 and 8 and put two zeros after the product)

147