Rounding to the Nearest 100 Worksheets

Rounding to the nearest 100 means replacing a number with the multiple of 100 that is closest to it, such as 347 with 300, or 562 with 600. The five PDFs on this page have rounding hills, tables for rounding to 100 and to 10 and 100 together, a color-by-rounding fish and a riddle, and every sheet has an answer key. They follow standard 3.NBT.A.1 of the Common Core standards for grade 3 number and operations in base ten, and the notes below show the rule, the numbers that round to each hundred and why the same number can round in opposite directions.

How to round to the nearest hundred

Look at the tens digit, not the ones. In 347 the tens digit is 4, so 347 rounds down to 300. In 352 the tens digit is 5, so it rounds up to 400. The ones digit never changes the answer when rounding to the nearest hundred.

Rounding the same number two ways

One of the worksheets asks for the nearest 10 and the nearest 100 side by side. 347 rounds to 350 but to 300: rounding to different places can give answers that go in opposite directions. Seeing that is one of the best ways to understand what “nearest” really means.

What is on this page

• Hundreds hills with tick marks every 10.
• Rounding tables: nearest 100, and nearest 10 and 100 together.
• Color by rounding: reveal a fish.
• Rounding riddle to the nearest 100.

Rounding to the nearest 100 worksheets: what is in the set

There are 5 rounding to the nearest 100 worksheets on this page, and every one has an answer key except for any cut-out games. One sheet is a set of rounding hills, two are tables of rounding to 100 and to 10 and 100 together, one is a color-by-rounding fish, and one is a riddle.

Rounding to the nearest 100 worksheets: look at the tens digit

The rounding to the nearest 100 worksheets use the same rule as rounding to the nearest ten, moved one place to the left: look at the tens digit. If it is 0 to 4, the number goes down to the hundred below, and if it is 5 to 9, it goes up to the next hundred. The ones digit never matters. Wikipedia’s article on rounding explains why. This table shows the three cases:

The ones digit is a good thing to ignore, since it is the part of the number that the rounding throws away. The rounding to the nearest 10 page has the first step, and the hundreds tens and ones page explains the hundreds, tens and ones that the rule uses.

Round to the nearest hundred: which numbers round to each hundred?

When children round to the nearest hundred, they can also ask which numbers round to 400. The answer is the 100 numbers from 350 to 449. This table shows the 100 numbers for each hundred from 100 to 1,000:

The halfway number 350 is the first to round up to 400, and 449 is the last to round down. The diagram above shows the three ranges next to each other. The number line tool shows the same idea on a line.

Round to the nearest hundred: the rounding hill

The rounding hill puts a hundred at each end, with the halfway number at the top, such as 350. A number on the left side rolls down to the left, and one on the right rolls to the right. The hills on the worksheets have tick marks every 10, so children can count the steps. This table shows six numbers and which hundred is closer:

The last column shows how much the number changes. The biggest change is 50, for a number such as 350 or 849, and the change is always between −49 and +50. On average the change is 25.0, for the 900 three-digit numbers.

Rounding to 10 and 100: two answers for one number

The sheet that asks for rounding to 10 and 100 side by side shows that the same number can have two different answers, which can go in opposite directions. 347 rounds up to 350 for the nearest 10, but down to 300 for the nearest 100. This table shows eight numbers rounded both ways:

Seeing this is one of the best ways to understand what “nearest” means: the answer depends on the place that you round to. How common are these opposite cases? This table counts the 900 three-digit numbers by what happens in each rounding:

25% of the numbers go up to the ten and down to the hundred, and 20% go down to the ten and up to the hundred. These are the cases that the sheet is built on.

Halfway numbers: the numbers that round up

The halfway numbers are 150, 250, 350 and so on, which are exactly 50 from each hundred. By the rule they round up. This is a convention, not a fact of nature, and some computer programs round halfway numbers to the nearest even hundred. This table shows six halfway numbers, with the steps to each hundred:

Children need only remember that a tens digit of 5 means round up. The rounding large numbers page shows that the rule works for bigger numbers too.

Rounding 3 digit numbers: how the 900 numbers share out

When rounding 3 digit numbers to the nearest hundred, the answer always ends in two zeros. Most hundreds get 100 numbers each, but the ends of the range are different, because there are no three-digit numbers below 100, and the numbers from 950 up round to a four-digit number. This table shows how the 900 numbers share out:

Only 50 three-digit numbers round to 100, and only 50 round to 1,000. Every other hundred has exactly 100. The number 1,000 is the only rounded value with four digits.

Rounding worksheets grade 3: the standard 3.NBT.A.1

For rounding worksheets grade 3, the standard is 3.NBT.A.1: use place value understanding to round whole numbers to the nearest 10 or 100. The five sheets in this pack cover both places, with the hills first, then tables, then the games. The Common Core standards for grade 3 number and operations in base ten list the other grade 3 standards for numbers. Children who are secure with both places can move on to rounding larger numbers in grade 4.

Where rounding to the nearest 100 is used

People round to the nearest hundred when they want a quick idea of a size. This table shows five facts, and how they are said when they are rounded:

A rounded number loses detail, but it is easier to say and to remember. The estimating with rounding page uses rounding to the nearest 100 to estimate sums and differences of 3-digit numbers.

Common mistakes with rounding to the nearest 100

The most common mistake is to look at the wrong digit. This table shows five mistakes, what went wrong and the fix:

Rounding to the nearest 100 word problems

Rounding comes up in populations, distances and counts. Ask children to circle the tens digit, to say which hundred is closer, and to write the rounded number:

Games and activities for rounding to the nearest 100

Children learn rounding to the nearest 100 best when they play with it. These games use things that are found at home or in a classroom:

• Number line walk: tape a line from 300 to 400 on the floor, and have each child stand on a number and walk to the closest hundred
• Rounding hill race: roll three dice for a number, and say where the ball rolls
• Round two ways: round a number to the nearest 10 and the nearest 100, and compare
• Rounding bingo: a bingo card with hundreds, and calling cards with numbers to round
• Closest hundred: pick a card and write the closest hundred on a whiteboard
• Color by rounding: solve the fish picture on this page and color by the key

Extra support and extra challenge with rounding to the nearest 100

For children who need more support: make sure that rounding to the nearest 10 is secure. Use a number line with marks every 10, and mark the two hundreds that the number is between. Circle the tens digit, and say whether it is less than 5. Use the answer key to check each hill, and keep to numbers such as 347 and 562 until the rule is automatic.

For children who need more challenge: ask for all the numbers that round to 700, for the smallest and biggest 3-digit numbers that round to 500, and for a number that rounds to 1,000 and has three digits. The sheet that rounds to both 10 and 100, and the riddle, are good challenges.

How to tell that a child is ready to move on from rounding to the nearest 100

Before moving on from rounding to the nearest 100, check that the child can do all four of these things:

1. The child finds the hundred below and the hundred above a number.
2. The child looks at the tens digit and decides which way to round.
3. The child rounds numbers such as 950 up to 1,000.
4. The child explains why a number can round in two directions at two places.

When all four are true, move on to the rounding large numbers page, or the estimating with rounding page.

A 20-minute lesson on rounding to the nearest 100

A short lesson is the best way to introduce rounding to the nearest 100. This 20-minute plan can be used in a classroom, at a tutoring session or at home, and it uses the worksheets at the end:

Where rounding to the nearest 100 fits across the grades

No skill stands alone. This table shows what children learn before and after rounding to the nearest 100, with the standard that goes with each step:

This page is the second of the rounding pages. The whole sequence is on the rounding worksheets page.

Helping at home with rounding to the nearest 100

Parents do not need to be experts to help with rounding to the nearest 100. These suggestions work well, and each takes only a few minutes:

• Round the cost of a trip, a meal or a game to the nearest hundred.
• Ask “which hundred is it closer to?” about numbers in the news.
• Use a ruler or a tape measure to show 350 as halfway.
• Round the same number to the nearest 10 and the nearest 100, and compare.
• Check the answers with the answer key, and ask the child to explain one.

How to check progress in rounding to the nearest 100

A teacher or parent can check progress in rounding to the nearest 100 with the answer key and a few questions. This table shows three common situations, what they mean and what to do next:

A five-day plan for rounding to the nearest 100

Most children need about a week of short sessions for rounding to the nearest 100. This plan follows the order of the worksheets on this page:

When the plan for rounding to the nearest 100 is complete, move on to the rounding large numbers page. The whole sequence is on the rounding worksheets page.