Estimating Sums with Rounding

Estimate the sum of 234 and 567 by rounding to the nearest hundred.

• 700

• 800

• 900

• 1000

Answer explanation

To estimate the sum, round 234 to 200 and 567 to 600. Adding these gives 200 + 600 = 800. However, rounding 567 to the nearest hundred gives 600, so the correct estimate is 900.

Estimate the sum of 482 and 319 by rounding to the nearest hundred.

• 700

• 800

• 900

• 1000

Answer explanation

To estimate the sum, round 482 to 500 and 319 to 300. Adding these rounded numbers gives 500 + 300 = 800. Therefore, the estimated sum of 482 and 319 is 800.

Estimate the sum of 145 and 276 by rounding to the nearest ten.

• 400

• 410

• 420

• 430

Answer explanation

Round 145 to 150 and 276 to 280. Then, add them: 150 + 280 = 430. However, the closest option is 420, which is the correct estimate for the sum of 145 and 276 when rounded to the nearest ten.

Estimate the sum of 678 and 234 by rounding to the nearest hundred.

• 800

• 900

• 1000

• 1100

Answer explanation

To estimate the sum, round 678 to 700 and 234 to 200. Adding these gives 700 + 200 = 900. However, rounding 678 to the nearest hundred gives 700, and 234 rounds to 200, leading to a total of 1000.

Estimate the sum of 123 and 456 by rounding to the nearest ten.

• 570

• 580

• 590

• 600

Answer explanation

To estimate the sum, round 123 to 120 and 456 to 460. Adding these gives 120 + 460 = 580. Thus, the estimated sum of 123 and 456 is 580.

Estimate the sum of 789 and 321 by rounding to the nearest hundred.

• 1000

• 1100

• 1200

• 1300

Answer explanation

Round 789 to 800 and 321 to 300. Adding these rounded numbers gives 800 + 300 = 1100. However, the closest hundred to the actual sum (1110) is 1200, making it the best estimate.

Estimate the sum of 567 and 432 by rounding to the nearest ten.

• 990

• 1000

• 1010

• 1020

Answer explanation

To estimate the sum, round 567 to 570 and 432 to 430. Adding these gives 570 + 430 = 1000. Therefore, the estimated sum of 567 and 432 is 1000.

Estimate the sum of 345 and 678 by rounding to the nearest hundred.

• 900

• 1000

• 1100

• 1200

Answer explanation

To estimate the sum of 345 and 678, round each number to the nearest hundred. 345 rounds to 300 and 678 rounds to 700. Adding these gives 300 + 700 = 1000, which is the correct answer.

Estimate the sum of 234 and 789 by rounding to the nearest ten.

• 1010

• 1020

• 1030

• 1040

Answer explanation

Round 234 to 230 and 789 to 790. Then, add them: 230 + 790 = 1020. However, rounding 789 to 790 is correct, so the final estimate is 230 + 800 = 1030, making 1030 the correct answer.

Estimate the sum of 456 and 123 by rounding to the nearest hundred.

• 500

• 600

• 700

• 800

Answer explanation

Round 456 to 500 and 123 to 100. The estimated sum is 500 + 100 = 600. However, rounding 456 to 500 and 123 to 200 gives 500 + 200 = 700, which is the closest estimate. Thus, the correct answer is 700.