7-1: Models
Make a model to show the product of 10 x 12.
10 x 10 = 100
10 x 2 = 20
100 + 20 = 120
40 x 10 = ?
400
Shayen wants to use rounding to estimate 42 x 87. What is her estimated product?
40 x 90 = 3,600
Her estimated product would be 3,600.
There are 24 schools competing in a cheerleading contest. There are 18 cheerleaders on each team. Which is the best way to use compatible numbers to estimate the total number of cheerleaders?
a) 20 x 10
b) 25 x 20
c) 30 x 10
d) 30 x 20
b) 25 x 20 = 500
25 x 40 = ?
25 x 40 = 1,000
Logan is passing out stickers to 43 students. He gave each student 10 stickers. How many total stickers did he pass out? Use a model to explain your answer.
10 x 40 = 400
10 x 3 = 30
400 + 30 = 430 stickers
70 x 40 = ?
2,800
Dylan spends 13 hours a week playing games. About how many hours does he spend playing games for 58 weeks?
10 x 60 = 600
About 600 hours
There are 24 rows in an auditorium. Each row has 42 seats. What is the best estimate of the total number of seats?
25 x 40 = 1,000
About 1,000 seats
What is the only bird that can fly backward?
Hummingbirds
A Virginia opossum can have up to 21 babies at one time. Suppose 10 Virginia opossums had babies all at the same time. How many baby opossums could there be? Use a model to explain your answer.
10 x 20 = 200
10 x 1 = 10
200 + 10 = 210 baby opossums
Which product is 4,000?
80 x 50 = 4,000
Carly wants to buy 45 sweaters for an event. Each sweater is $15. About how much will she spend total?
50 x 20 = 1,000
About $1,000
Noah is making centerpieces for an event. He is putting 22 roses in each centerpiece. Use compatible numbers to estimate the number of roses he will need for 26 centerpieces.
20 x 25 = 500
About 500 roses.
Zoe V. uses 6 apples and 2 bananas to make a fruit salad. She puts twice as many oranges as bananas in the salad. How many pieces of fruit will she use to make 2 fruit salads?
Oranges= 4
6 + 2 + 4 = 12
2 fruit salads = 12 x 2
24 pieces of fruit.
Reese is making 20 necklaces. Each necklace has 16 beads. How many beads does she need to make all of the necklaces? Use a model to explain your answer.
20 x 10 = 200
20 x 6 = 120
200 + 120 = 320 beads
100 x 20 = ?
2,000
Ayaan is making 68 cupcakes. Each cupcake will have 29 sprinkles. About how many sprinkles will Ayaan use total?
70 x 30 = 2,100
About 2,100 sprinkles
Scarlett needs to explain why the best estimate of 23 x 62 is by rounding 23 -> 25 and not 20. Why did Scarlett round 23 to 25?
(Sample answer): Scarlett rounded 23 to 25 and not 20 because she is finding the best estimate. 25 is closer to 23. The equation would be 25 x 60 = 1,500.
What is the capital of California?
Sacramento
Owen is using a model to explain 50 x 23. What are the partial products he needs to find the final product?
50 x 20 = 1,000
50 x 3 = 150
1,000 and 150
Which product is 8,000?
200 x 40 = 8,000
or
20 x 400 = 8,000
Cameron is estimating 14 x 32. He says that the estimated product of 10 x 30 will be less than the actual product. Explain if he is correct.
(Sample answer): Cameron is correct because 14 x 32 rounds down to 10 x 30. The estimated product would be an underestimate.
25 x 90 = 2,250
Remy sold 8 ribbons and 6 pins at a craft fair. He sold the ribbons for $3 each and the pins for $2 each. How much money did Remy earn?
8 x 3 = 24
6 x 2 = 12
24 + 12 = 36
$36