Learning Rounding: Help for Struggling Students

A Guide for Rounding

When you're rounding whole numbers, you'll need to identify different place values within a number. The number farthest to the right in a whole number is in the ones place, and the number to the left of the ones place is in the tens place. To the left of the tens place, you'll find the hundreds place.

For example, the number 53 has a three in the ones place and a five in the tens place. The number 253 is the same, except that it also has a two in the hundreds place.

Nearest Ten

To round a number to the nearest ten, you'll convert it to the closest number on the number line that ends in zero, like 30 or 50. The digit in the ones place of the original number tells you whether you should round up or down.

Numbers with one through four in the ones places are rounded down to the closest lower number that ends in zero. Numbers that end in six through nine are rounded up to the closest higher number that has a zero in its ones place. Numbers that end in five are at the midpoint between the closest numbers ending in zero, but they are always rounded up. Here are some examples:

11 rounds to 10

15 rounds to 20

17 rounds to 20

You can also round larger numbers to the nearest ten:

322 rounds to 320

325 rounds to 330

329 rounds to 330

Nearest Hundred

When you round a number to the nearest hundred, you're finding the closest number on the number line that has a zero in both the ones and tens places, like 100 or 500. The digit in the original number's tens place tells you whether to round up or down. Numbers that have a one, two, three or four in their tens places are rounded down, while those with fives through nines in their tens places are rounded up. Here are a few examples:

127 rounds to 100

150 rounds to 200

173 rounds to 200

Even 2-digit numbers can be rounded to the nearest hundred. Notice that you still decide to round up or down based on the number in the tens place:

37 rounds to zero

50 rounds to 100

93 rounds to 100