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Name _ Reteaching 8-2 Estimating Products £ f M - . for q When you are working with fractions and mixed numbers, you can estimate using rounding, compatible numbers, or compatible benchmark fractions. lo Estimate x 12 using a compatible benchmark fraction. Estimate 130 X 21 using a whole number that is compatible with the denominator. 130 w Change 21 to the nearest whole number that is compatible with 10. x 21 w 130 w 10 w 1 x 12 = 3 ?o x 20 = 6 ~ x 21 ~ 6 lo 1 x 12 4 Think: 20 .;..10 3 x 2 = = ~10 x 12 ~ 3 2. Round to a compatible benchmark fraction. Since is close to and 4 is a factor of twelve, use lo 1- Think: 12 -;-4 = 3. 1 x 3 = 3. 6. ffif61? U!! Estimate each product by using compatible numbers or benchmark fractions. 19 = 1. 1x 6 4. 31 x 25 2. = 1x 10 = 3. 7 5. Lx 12 8 x 90 6. JL 16 18 = = 4_ 8. 35 x~= 12 7. 43 x 27 = Q x 23 = 9. 16 x 9- Estimate each product by rounding each factor to the nearest whole number. 10. 6~ x 5i -7 Round 6~:' Round 5i: Multiply: _ 6 11. 102x4Q 13. 4~ x 21 = = 96---- _ 14. Reasonableness Carlotta estimated that ~ x 20 is about ~ x 14 = 6. Is her estimate reasonable? Why or why not? 15. Critical Thinking Why are the estimates of 160 x 18 shown below different? Is one estimate better than the other? .e. x 10 24 18 ~ ..§... x 20 = 12 Topic 8 10 160 x 18"" -21 x 18 = 9. 16. Show three ways to estimate lx 5lldentify each method you use. 17. Explain It Mr. Simpson lives 11130 miles from his office. He estimates that he commutes 11 x 2 x 5, or 110 miles each week. Is his estimate an overestimate or an underestimate? Explain. 18. Which benchmark fraction could you use to estimate the product of 38 x l2 ? 19. Geometry Which is the best estimate for the area of a square with sides equal to inches? A _ 3i- 3 sq in. S 6 sq in. C 9 sq in. D 16 sq in. 20. Joyce and Marianne have money jars. Joyce has 54 dimes in her jar. Marianne has 190 as many dimes as Joyce. Estimate the number of dimes that Marianne has in her jar. A co jj ~g o ~c 60 dimes S 45 dimes C 6 dimes D 5 dimes g 1; '" D@ Topic 8 25