Rounding and Estimation

Round 54 to the nearest ten.

• 40

• 50

• 60

• 70

Answer explanation

The digit in the ones place is 4. Since 4 is 4 or less, so round down: keep the tens digit (5) and change the ones digit to 0. Therefore, the rounded number is 50.

Estimate the sum of 35 and 64.

• 90

• 110

• 80

• 100

Answer explanation

When estimating, round each number to the nearest ten and then add them together. Rounded to the nearest ten, 35 becomes 40 and 64 becomes 60. Adding these rounded numbers (40 + 60) gives an estimated sum of 100.

 Round 650 to the nearest hundred.

• 600

• 650

• 700

• 750

Answer explanation

The digit in the tens place is 5, which is 5 or more, so round up: increase the hundreds digit (6) by 1 to become 7 and change the tens and ones digits to 0. Therefore, the rounded number is 700.

Estimate the difference between 807 and 469.

• 300

• 200

• 500

• 400

Answer explanation

When estimating, round each number to the nearest hundred and then subtract the rounded numbers. Rounded to the nearest hundred, 807 becomes 800 and 469 becomes 500. Subtracting these rounded numbers (800 - 500) gives an estimated difference of 300.

Round 3,982 to the nearest thousand.

• 2,000

• 5,000

• 3,000

• 4,000

Answer explanation

The digit in the hundreds place is 9, which is 5 or more, so round up: increase the thousands digit (3) by 1 to become 4 and change the hundreds, tens, and ones digits to 0. Therefore, the rounded number is 4,000.

Estimate the sum of 6,801 and 1,970.

• 8,000

• 7,000

• 9,000

• 10,000

Answer explanation

When estimating, round each number to the nearest thousand and then add them together. Rounded to the nearest thousand, 6,801 becomes 7,000, and 1,970 becomes 2,000. Adding these rounded numbers (7,000 + 2,000) gives an estimated sum of 9,000.

Round 15 to the nearest ten.

• 10

• 30

• 20

• 40

Answer explanation

The digit in the ones place is 5. Since 5 is 5 or more, so round up: add 1 to the tens digit (1) to become 2 and change the ones digit to 0. Therefore, the rounded number is 20.

Estimate the difference between 78 and 56.

• 10

• 20

• 30

• 40

Answer explanation

When estimating the difference, round each number to the nearest ten and then find the difference. Rounded to the nearest ten, 78 becomes 80, and 56 becomes 60. Subtracting these rounded numbers (80 - 60) gives an estimated difference of 20.

Round 349 to the nearest hundred.

• 300

• 350

• 400

• 450

Answer explanation

The digit in the tens place is 4, which is 4 or less, so round down: keep the hundreds digit (3) and change the tens and ones digits to 0. Therefore, the rounded number is 300.

Estimate the sum of 532 and 879.

• 1,400

• 1,500

• 1,600

• 1,700

Answer explanation

When estimating, round each number to the nearest hundred and then add them together. Rounded to the nearest hundred, 532 becomes 500 and 879 becomes 900. Adding these rounded numbers (500 + 900) gives an estimated sum of 1,400.