Worksheet: Estimating Decimals Sums

In this worksheet, we will practice estimating the sum of two decimal numbers by rounding to the nearest whole number or using compatible numbers.

Q1:

Calculate 6.76+20.73, rounding your answer to the nearest whole number.

Q2:

1 . 3 5 6 5 + 2 . 2 5 2 to the nearest thousandth.

Q3:

Complete 82371,000+389200 to the nearest hundredth.

Q4:

5 4 9 9 2 , 0 0 0 + 7 1 , 3 1 1 2 , 5 0 0 to the nearest thousandth.

Q5:

Two pieces of cloth are 291.67 m and 455.196 m long. Find the sum of their lengths. Give your answer to the nearest hundredth of a meter.

Q6:

8 . 6 7 6 + 5 . 6 9 to the nearest hundredth.

Q7:

Consider this addition problem.

Estimate the total by rounding each number to the nearest whole number.

Calculate the total.

Check that your answer is reasonable using your estimate.

Q8:

Estimate the sum 15.7+7.3 by rounding each decimal to the nearest whole number.

Q9:

Estimate the sum 16.89+11.62 by rounding each decimal to the nearest whole number.

Q10:

Chloe knows how to add and subtract 0, 0.25, 0.5, 0.75, and 1. Look at how she uses these numbers to help her estimate the sums of decimal numbers.

By rounding to the nearest multiple of 0.25, she finds that 1.31+0.42 is about 1.75.

Estimate the sum by rounding each number to the nearest multiple of 0.25.

Q11:

Estimate the sum 2.15+1.89 by rounding each number to a benchmark.

Hint: Benchmarks are numbers like 0.25, 0.5, 0.75, or 1.

Q12:

Sophia bought a pencil for $3.29 and a book for $9.75. About how many dollars did Sophia pay?

Hint: Round each amount to the nearest dollar.

Q13:

Estimate the sum by rounding each number to a benchmark.

Hint: Benchmarks are numbers like 0.25, 0.5, 0.75, or 1.

0 . 8 9 + 0 . 1 3

Q14:

You have uploaded two videos with lengths 3.9 minutes and 5.38 minutes. About how many minutes do you need to watch both videos?

Hint: Round each number to the nearest minute.

Q15:

James is buying items on his shopping list.

Estimate the total cost of the items on the list.

Q16:

Look at how Mason estimates the sum of decimal numbers by rounding each number to the nearest whole number.

He found that the sum of 4.6 and 5.32 is about 10.

Estimate the following sum by rounding each number to the nearest whole number.8.69+3.25

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