2.13 Estimation to help with multiplication and division

Which of these options is most logical to estimate the product of 23 and 5?

• I could use 20 x 5 to estimate

• I could use 30 x 5 to estimate

• I could use 23 x 10 to estimate.

Why would using 20 x 5 be a logical way to estimate the product of 23 and 5?

• because 23 rounds down to 20

• because 23 is about 25

• because 23 rounds up to 30

Estimate the product of 23 and 5.

• 110

• 30

• 100

• 50

Which is the most friendly way to estimate the product of 47 and 8?

• 45 x 8

• 50 x 10

• 45 x 5

Estimate the product of 47 and 8.

• 300

• 500

• 600

• 400

Which is the most friendly way to estimate the product of 56 and 32?

• 60 x 30

• 60 x 40

• 55 x 30

Estimate the product of 56 and 32.

• 1800

• 2400

• 2000

• 1600

Which is the most friendly way to estimate the product of 74 and 63?

• 80 x 70

• 75 x 60

• 70 x 60

Estimate the product of 74 and 63.

• 5200

• 3800

• 4400

• 4200

Estimate the product of 45 and 9.

• 550

• 400

• 450