Estimating Answers to Addition and Subtraction Problems: Practice Quiz

Question 1

An estimate is:

Accepted Answer

A close guess to the answer of a calculation

Answer

The precise answer to a calculation

Answer

A number that is always larger than the actual answer

Answer

A number that is always smaller than the actual answer

Question 2

Which of the following is NOT a factor to consider when estimating the answer to an addition or subtraction problem?

Accepted Answer

The units of measurement being used

Answer

The size of the numbers

Answer

The operation (addition or subtraction)

Answer

The number of digits in each number

Question 3

To estimate the answer to 643 + 289, it is most appropriate to round both numbers to the nearest:

Accepted Answer

100

Answer

10

Answer

1,000

Answer

10 and 100

Question 4

Which tip is helpful for estimating the answer to an addition problem?

Accepted Answer

Estimate the sum of the tens digits and the ones digits separately.

Answer

Round both numbers to the nearest multiple of 5.

Answer

Round both numbers to the nearest power of 10.

Answer

Add the digits of each number separately.

Question 5

When estimating answers with decimals, you can:

Accepted Answer

Round the decimals to the nearest whole number.

Answer

Use a calculator.

Answer

Guess and check.

Answer

Use mental math.

Question 6

Which method could you use to estimate the answer to 45 + 27?

Accepted Answer

Round 45 to 50 and 27 to 30, then add.

Answer

Round 45 to 40 and 27 to 30, then subtract.

Answer

Double the smaller number and then add the larger number.

Answer

Halve the larger number and then multiply by the smaller number.

Question 7

To estimate the sum of 485 and 213, which of the following is the closest estimate?

Accepted Answer

700

Answer

800

Answer

900

Answer

500

Question 8

Estimate the sum of 358 and 246 to the nearest hundred.

Accepted Answer

600

Answer

500

Answer

400

Answer

700

Question 9

Which of the following is a limitation of estimating the answer to an addition or subtraction problem?

Accepted Answer

It does not always provide an exact answer

Answer

It helps check the reasonableness of the answer

Answer

It saves time

Question 10

Which of the following estimation strategies involves adjusting one number up and the other number down by the same amount?

Accepted Answer

Compensating

Answer

Rounding

Answer

Front-end estimation

Question 11

Which of the following is the closest estimate for the difference between 567 and 299?

Accepted Answer

300

Answer

400

Answer

200

Answer

500

Question 12

A rectangular garden has a length of approximately 120m and a width of approximately 80m. Estimate the perimeter of the garden.

Accepted Answer

400m

Answer

300m

Answer

500m

Answer

600m

Question 13

A farmer has around 460 sheep and sells approximately 190 of them. Estimate the number of sheep the farmer has left.

Accepted Answer

270

Answer

280

Answer

260

Question 14

A rectangular garden is approximately 150m long and 70m wide. Estimate the area of the garden.

Accepted Answer

1000m²

Answer

1200m²

Answer

1100m²

Answer

900m²

Question 15

A school has approximately 520 students, and about 220 of them are girls.  About how many students are boys?

Accepted Answer

300

Answer

500

Answer

400

Answer

200

Question 16

You have £5.70 and spend approximately £2.80 on a book. Is it closer to having £2 left over or £3 left over?

Accepted Answer

£3

Answer

Not enough information to tell

Answer

It's exactly halfway between

Answer

£2

Question 17

A farmer has about 390 sheep and buys approximately 110 more. Without calculating the exact number, would he have more or less than 500 sheep?

Accepted Answer

More than 500

Answer

Less than 500

Answer

Exactly 500

Answer

It's impossible to tell without exact calculation

Question 18

A bus has approximately 50 passengers, and about 20 get off. Is the number of passengers left closer to 20 or 30?

Accepted Answer

30

Answer

20

Answer

Not enough information to tell

Answer

It's exactly halfway between

Question 19

You want to buy a toy for approximately £13 and a game for approximately £8. Would you need closer to £20 or £25 to buy both?

Accepted Answer

£20

Answer

Not enough information to tell

Answer

It's exactly halfway between

Answer

£25

Question 20

A recipe calls for 180 ml of milk, but you only have 90 ml.  Would you need more or less than 100 ml more to have enough?

Accepted Answer

More than 100 ml

Answer

Less than 100 ml

Answer

It's impossible to tell without exact calculation

Question 21

Which of the following is the best estimate for the sum of 245 and 138?

Accepted Answer

400

Answer

300

Answer

500

Question 22

What is the best estimate for the difference between 456 and 278?

Accepted Answer

200

Answer

300

Answer

180

Answer

100

Question 23

To estimate the sum of 345 and 267, which rounding method is most appropriate?

Accepted Answer

Rounding to the nearest ten

Answer

Rounding to the nearest million

Answer

Rounding to the nearest thousand

Answer

Rounding to the nearest hundred

Question 24

Which rounding method is most suitable for estimating the difference between 543 and 298?

Accepted Answer

Rounding to the nearest ten

Answer

Rounding to the nearest thousand

Answer

Rounding to the nearest hundred

Answer

Rounding to the nearest million

Question 25

What is the estimated answer when you add 456 and 345?

Accepted Answer

800

Answer

900

Answer

1000

Answer

700

Question 26

Estimate the answer when you subtract 234 from 567.

Accepted Answer

300

Answer

500

Answer

400

Answer

200

Question 27

What is the best estimate for the total of 123, 456, and 789?

Accepted Answer

1400

Answer

1300

Answer

1000

Answer

1500

Question 28

Estimate the answer when you subtract 234 and 123 from 456.

Accepted Answer

100

Answer

300

Answer

200

Answer

400

Question 29

A school has 345 students in Year 5 and 278 students in Year 6. Roughly how many students are in the school?

Accepted Answer

600

Answer

500

Answer

700

Answer

800

Question 30

Apples cost 25p each. About how much would it cost to buy 145 apples?

Accepted Answer

£35

Answer

£25

Answer

£45

Answer

£15