Show:
Estimation and Mental Math
Double Digits
Word Problems #1
Word Problems #2
Writing to Explain
100
Use mental math. What is the product of 80*40?
3200
100
15*21
315
100
Karen has 13 spools of ribbon. Each spool has 32 feet of ribbon. How many feet of ribbon does Karen have altogether?
13*32= 416 feet of ribbon
100
For a community service project, 22 classes collected 82 pounds of canned goods. How many total pounds did they collect?
1804 pounds
100
Explain why the product of 40*50 has three 0's, when 40 only has one 0 and 50 only has one 0.
Because the product of 4*5 (20) already has a 0 at the end, you have to make sure you still add the two 0's back on at the end. That means you will get 2000 as your product. When the the initial product is a multiple of ten, you have to make sure you still add on the zeros you cover up to multiply.
200
Estimate by rounding to the nearest ten. 51*83
4000
200
81*34
2754
200
Jake can make 50 cookies with one tub of cookie dough. If she buys 10 tubs of cookie dough, how many cookies can she make?
500 cookies
200
There are 60 stickers on a sheet. How many stickers are on 20 sheets?
1200 stickers
200
Sarah uses rounding to estimate that the product of 42 and 58 is 2400. Is this estimate reasonable? Why or why not? How did she get this answer?
This answer is reasonable because she rounded 42 to 40 and 58 to 60. When she multiplied those two numbers together she got 2400. If you find the actual answer, you get 2,356, which is reasonably close to estimate.
300
Coach Kyle ordered 17 soccer jerseys for his team. If each jersey costs $22, what is the best estimate for how much the jerseys will cost before tax?
$400
300
67*52
3483
300
There are 10 students in the piano concert. If each student performs for 15 minutes, how long is the concert going to last?
150 minutes or 2 hours and 30 minutes
300
Piper has 42 scrapbook pages. Each page has 15 pictures on it. How many pictures are in Piper's scrapbook?
42*15= 630 pictures
300
A ticket for an adult to go to the zoo costs $6. A child tickets costs $4. How much would it cost 4 adults and 5 children to go to the zoo? How did you get this answer?
To find the price of the adult tickets you need to find 4*6=24. For the children tickets, you need to find 4*5=20. Then you add the two costs together to get the total. $24+$20= $44.
400
Jesse makes $86 a week by tutoring. ABOUT how much money can he make in 22 weeks?
$1800
400
99*22
2178
400
Layla bought 6 bouquets of flowers for $36. How much would she have spent if she bought 8 bouquets?
36/6= $6 each $6*8= $48
400
At summer camp, each camper gets 12 minutes of computer time each day. If there are 43 campers, how much time is needed for each camper to get computer time?
516 minutes
400
Why is the product of 82*21 equal to the sum of 80*21 and 2*21?
The distributive property tells us that we can break apart multiplication problems to make them easier to solve. We can break 82 into tens and ones to make it easier to multiply. Once we have figured out the two partial products we must add them together to get the total product for 82*21.
500
Katie makes $42 a week babysitting. ABOUT how much can Katie make in one year? (There are 52 weeks in one year)
$2000
500
54*72
3888
500
The bathroom floor is covered in tile. The tiles are in 35 rows of 42 tiles. How many tiles are covering the floor?
1470 tiles
500
Mrs. Farthing bought 36 new books for each classroom at Prairie Star. If PSE has 26 classes, how many books did Mrs. Farthing buy?
936 books
500
Jesse rides his bike for 2 hours a day! How many hours does Jesse ride in 3 weeks? Explain your work. What steps did you take?
First you have to figure out how many hours Jesse rides in one week. Since there are 7 days in one week, we have to take 2*7 to figure out how many hours he rides a week. Since he rides 14 hours a week, you have to multiply 14*3 to figure out how many hours he rides for three weeks! 14*3= 42, so her rides for 42 hours a week.