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Estimation
Break Apart
Compensation
Word Problems
Multiplication
100
Estimate the following product. 457 X 9
About 450
100
What is 25 X 7
175
100
Use compensation to solve. 18 X 3
Round to 20 then multiple by 3 to get 60. Subtract 6 to get the final product of 54.
100
Mr. Howard arranged his desks with five rows with seven desks in each row. How many desks does he have in the classroom?
35 desks.
100
89X6
534
200
Estimate the following product. 4,569 X 2
About 10,000
200
56 X 4
224
200
78 X 4
Round up to 80 then multiply by 4 to get 320. Subtract 8 to get the final product of 312.
200
Erika wants to give 5 stickers to everyone in her class. Her class sits in 4 rows of 8. Erika says she needs 140 stickers. Is she correct? Why or why not?
She is incorrect. She actually needs 160 stickers. First I had to find the number of students that were in her class which is 32 students. Then I multiplied 32 by 5 to find the total number of stickers needed.
200
731 X 8
5,768
300
Estimate the following product. 57 X 9
540
300
78 X 4
312
300
64 X 5
Round down to 60 then multiply by 5 to get 300. Then add 20 to get the final product of 320.
300
Marisa says 302 X 6 = 192. Is she correct? explain why her answer is reasonable or not reasonable.
She is incorrect. When I multiple 302 by 6 I got the final product of 1,812, which is much larger than 192.
300
321 X 9 = ?
2,889
400
Round to the nearest 10s place then estimate to solve. 123 X 5
600 (120 X 5)
400
99 X 9
891
400
58 X 2
Round Up to 60 then multiply it by 2 to get 120. Then, subtract 4 to get the final product of 116.
400
Jamie practiced his spanish skills for about 11 hours every week for 8 weeks About how many hours did he practice in all? How can you check your work? Is the estimation reasonable?
He practiced for about 80 hours in total. I found this by rounding to the nearest 10s place and then multiplied by 8 to get my estimation of 80. I can check my estimation by multiplying 8 by 11 which equals 88. My answer is reasonable because 80 is close to 88.
400
9 X 45
405
500
9872 X 5
50,000
500
76 X 8
608
500
23 X 9
Round down to 20 then multiply it by 9 to get 180. Add 27 to get the final product of 207.
500
There are 5 animals on a far. Each animal eats 105 pounds of food per week. How much food does the farmer have to buy each week? Draw a model to help solve and explain your reasoning? How do you know if your answer is reasonable?
105 X 5 = 525. I found this answer by using the break apart method to find my partial products then I added my partial products to find my product. My answer is reasonable because when I round 105 to 110 and then multiple, I get the product of 550 which is close to 525. *You can also round down to 100 *Mr. Howard will check models
500
5432 X 2
10,864