envision math topic 5: lesson 5-3 & 5-4 combined multiplying by 1-digit numbers:
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EnVision Math Topic 5: Lesson 5-3 & 5-4 Combined Multiplying by 1-Digit Numbers: Using Rounding to Estimate 2010-11. Sarah earns $48 a week babysitting. She has saved all her money for the past 6 weeks. About how much money has she earned?. About. - PowerPoint PPT PresentationTRANSCRIPT
EnVision Math
Topic 5:
Lesson 5-3 & 5-4 Combined
Multiplying by 1-Digit Numbers:
Using Rounding to Estimate
2010-11
Sarah earns $48 a week babysitting. She has saved all her money for the past 6 weeks. About how much money has she earned?
About
How can I
estimate products
?
645 + 253 =600 300
900
72,694 - 17,789 =70,000 20,000
50,000
52 x 9 =50 x 9
450
6 x 34 =6 x 30
180
314 x 7 =300 x 7
2,100
3 x 538 =5003 x
1,500
39 x 5 =40 x 5
200
9 x 602 =9 x 600
5,400
3 x 86 =3 x 90
270
486 x 7 =500 x 7
3,500
77 x 8 =80 x 8
640
2 x 863 =2 x 900
1,800
3,752 x 9 = 4,000 x 9
36,000
7 x 5,835 =7 x 6,000
42,000
6,987 x 8 = 7,000 x 8
56,000
4 x 5,125 = 4 x 5,000
20,000
Sarah earns $48 a week babysitting. She has saved all her money for the past 6 weeks. About how much money has she earned?
50 x 6 =$300
There are 78 fifth grade students at Lincoln Elementary. Each fifth grader brought in 7 cans for the recycling drive. About how many cans did the fifth graders collect?
80 x 7 = 560 cans
Ursula has an album that she keeps pressed flowers in. The album has 34 pages, and each page has 7 pressed flowers. Which of the following shows a reasonable estimate for how many pressed flowers Ursula has?
A. 40 x 7 = 280 pressed flowers
B. 30 x 7 = 210 presses flowers
C. 40 x 10 = 400 pressed flowers
D. 30 x 10 = 300 pressed flowers
Isabelle has 9 ant farms. Each ant farm has 99 ants. Which of the following is a reasonable estimate of how many ants Isabelle has?
A. 9 x 90 = 810 ants
B. 10 x 100 = 1,000 ants
C. 9 x 80 = 720 ants
D. 9 x 100 = 900 ants
How can I use estimation to check if my answer is
reasonable?
There are 5 animals on a farm. Each animal eats 105 pounds of food per week. How much food does the farmer have to buy each week?
105 x 5 = 525 pounds of food100 x 5 = 500
Kenny has 7 pouches. Each pouch has 21 marbles. How many marbles does Kenny have?
7 x 21 = 147 pouches
7 x 20 = 140
marbles
A fish store has 3 empty tanks. After a delivery, they put 29 fish in each tank. How many fish were in the delivery?
3 x 29 = 627 fish
3 x 30 = 90
87