Practice
Name
Using Mental Math to Multiply
5-4
Use compensation to find each product.
1. 34 × 4 = 136 2. 199 × 6 =1,194
3. 53 × 7 = 371
4. 505 × 4 =2,020
5. 41 × 6 = 246
6. 298 × 6 =1,788
7. 76 × 5 = 380 8. 803 × 7 = 5,621
9. 83 × 3 = 249
10. 390 × 2 = 780 11. 28 × 8 = 224 12. 709 × 4 = 2,836
13. 94 × 2 = 188
14. 410 × 8 =3,280
15. 16 × 4 = 64
16. 197 × 5 = 985 17. 46 × 5 = 230
18. 896 × 9 =8,064
19. Reasonableness Quinn used compensation to find the
product of 37 × 4. First, she found 40 × 4 = 160. Then she
adjusted that product by adding 3 groups of 4 to get her final
answer of 172. What did she do incorrectly?
Quinn should have adjusted the product,
160, by subtracting 3 groups of 4,
instead of adding 3 groups of 4. The
correct answer is 160 2 12 5 148.
20. Davidson’s Bakery uses 9 dozen eggs to make
cookies each day. There are twelve eggs in one
dozen. How many eggs do they use?
A 90
B 98
C 108
D 112
21. Writing to Explain Find the product of 503 × 6. Explain how
you found the product.
3,018; Sample answer: I multiplied 500
by 6 to get 3,000. Then I added three
groups of 6, or 18 to that product.
P 5•4
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