Rounding to the Nearest 10, 100, and 1,000

Rounding swaps an exact number for a nearby benchmark that is easier to use. We round to the nearest 10, 100, or 1,000 to estimate sums, compare large numbers, or report data without showing every digit.

The Rounding Rule

• Find the digit in the place you are rounding to — this is the rounding digit.
• Look at the digit one place to its right — this is the deciding digit.
• If the deciding digit is 5 or more, round up: add 1 to the rounding digit.
• If the deciding digit is less than 5, round down: keep the rounding digit the same.
• Replace every digit to the right of the rounding place with zero.

Rounding to the Nearest 10

• Look at the ones digit — that is the deciding digit.
• If ones is 5 to 9, round the tens digit up; if ones is 0 to 4, keep the tens digit.
• Example: 2,347 — ones is 7, so round up to 2,350.
• Example: 8,142 — ones is 2, so round down to 8,140.

Rounding to the Nearest 100

• Look at the tens digit — that is the deciding digit.
• If tens is 5 to 9, round the hundreds digit up; if tens is 0 to 4, keep the hundreds digit.
• Example: 46,572 — tens is 7, so round up to 46,600.
• Example: 13,239 — tens is 3, so round down to 13,200.

Rounding to the Nearest 1,000

• Look at the hundreds digit — that is the deciding digit.
• If hundreds is 5 to 9, round the thousands digit up; if hundreds is 0 to 4, keep the thousands digit.
• Example: 27,650 — hundreds is 6, so round up to 28,000.
• Example: 91,408 — hundreds is 4, so round down to 91,000.

The Halfway Trick

• Find the two benchmarks the number sits between (for nearest 10: the two tens it falls between).
• Find the halfway point — exactly 5 above the lower benchmark.
• If the number is at or above the halfway point, round up. If it is below, round down.
• Example: 2,347 sits between 2,340 and 2,350; halfway is 2,345. 2,347 is above 2,345, so round up to 2,350.