Estimating Sums Worksheet

Estimating Sums

Read each question carefully and follow the instructions to estimate the sums. Show your work where indicated.

Round each number to the nearest ten, then estimate the sum.

1. 37 + 52 ≈  

2. 81 + 19 ≈  

3. 123 + 48 ≈  

4. 256 + 73 ≈  

Round each number to the nearest hundred, then estimate the sum.

1. 145 + 289 ≈  

2. 309 + 471 ≈  

3. 562 + 138 ≈  

4. 780 + 210 ≈  

Choose the best estimate for each sum.

1. 412 + 387

2. 67 + 23 + 48

Estimate the sum for each word problem. Show your rounding.

1. Sarah bought a book for $18 and a toy for $32. Approximately how much did she spend in total?

2. A school has 457 students in the junior section and 321 students in the senior section. About how many students are there in total?

Determine if the following statements are true or false.

1. The estimated sum of 149 and 251 (rounded to the nearest hundred) is 400.

2. When estimating 78 + 12 by rounding to the nearest ten, the estimated sum is 90.

Explain why estimating sums can be useful in everyday life.