X Tables
Place Value

Rounding to the nearest 100

Build rounding rules from place-value reasoning.

Quick answer

To round a number to the nearest 100, look at the tens digit. If it is 5 or more, round up to the next hundred. If it is less than 5, round down to the previous hundred.

Learning outcome

By the end of this page, you will be able to round any number to the nearest 100 by looking at the tens digit and deciding whether to go up or down. Success signs:
  • You can explain why we round numbers
  • You can identify the tens digit in a number
  • You can round numbers like 347 or 862 to the nearest 100
  • You can use rounding to estimate answers quickly

Why this matters

Rounding to the nearest 100 helps us make numbers easier to work with and understand. When you're shopping and want to quickly estimate how much money you need, or when you're planning a party and need to guess how many guests might come, rounding helps you make quick decisions. In maths, rounding helps you check if your answers are reasonable. It's also useful when you're measuring things like the height of a tree or the distance between two places.

How it works

Rounding to the nearest 100 works by looking at the tens digit of a number. Here's how:
  1. Find the hundreds digit in your number
  2. Look at the tens digit (the digit just to the right of the hundreds)
  3. If the tens digit is 5 or more, round up to the next hundred
  4. If the tens digit is less than 5, round down to the previous hundred

Examples you can see

Let's try some examples together. Example 1: 432
  • The hundreds digit is 4
  • The tens digit is 3
  • Since 3 is less than 5, we round down
  • 432 rounds to 400
Example 2: 768
  • The hundreds digit is 7
  • The tens digit is 6
  • Since 6 is 5 or more, we round up
  • 768 rounds to 800
Example 3: 250
  • The hundreds digit is 2
  • The tens digit is 5
  • Since 5 is 5 or more, we round up
  • 250 rounds to 300
Let's think about this like a number line. Imagine numbers 200 to 300 lined up. The middle point is 250. Numbers from 200 to 249 round down to 200. Numbers from 250 to 300 round up to 300.

Try it as a mini adventure

The Great Rounding Quest You are a treasure hunter exploring an ancient castle. The castle has a magical room with numbers on the walls. Your mission is to round these numbers to the nearest 100 to unlock the next door. First stop: 347 What number does 347 round to? Second stop: 682 What number does 682 round to? Third stop: 153 What number does 153 round to? Fourth stop: 999 What number does 999 round to? Fifth stop: 400 What number does 400 round to? Final stop: 550 What number does 550 round to? Can you solve all the riddles and find the treasure?

Common mistakes

  • Mistake: Thinking that 450 rounds to 400 because 5 is in the tens place. Why it happens: Children often forget that when the tens digit is exactly 5, we round up. Fix: Remember: 5 or more means round up!
  • Mistake: Looking at the ones digit instead of the tens digit. Why it happens: Children sometimes get confused about which digit to look at. Fix: Always look at the tens digit to decide whether to round up or down.
  • Mistake: Rounding 500 to 400. Why it happens: Confusion about numbers exactly at the halfway point. Fix: When a number is exactly halfway (like 500), we round up to the next hundred.

Parent and carer guide

To help your child with rounding to the nearest 100:
  1. Start by practicing with smaller numbers like 100 to 200
  2. Use everyday examples like shopping prices or distances
  3. Ask questions like "What do you think 347 rounds to?" and wait for their reasoning
  4. Check that they understand the tens digit is the key number
  5. Use visual aids like number lines or hundreds charts
  6. Be patient if they make mistakes - it's part of learning!
What to say:
  • "Let's look at the tens digit together"
  • "What happens when we round 672?"
  • "Can you explain how you decided to round up or down?"
What not to worry about:
  • Your child might sometimes get confused at first
  • They might make a few mistakes before getting it right
  • It's normal for rounding to take a bit of practice

Practice questions

  1. Round 234 to the nearest 100
  2. Round 567 to the nearest 100
  3. Round 149 to the nearest 100
  4. Round 782 to the nearest 100
  5. Round 350 to the nearest 100
  6. Round 899 to the nearest 100
  7. Round 400 to the nearest 100
  8. Round 650 to the nearest 100
Answers:
  1. 200
  2. 600
  3. 100
  4. 800
  5. 400
  6. 900
  7. 400
  8. 700

FAQ

What does it mean to round a number?

Rounding a number means making it simpler by changing it to the nearest hundred, ten, or other place value.

Why do we need to round numbers?

We round numbers to make them easier to work with, estimate totals quickly, or give approximate answers when exact numbers aren't needed.

What if the tens digit is exactly 5?

If the tens digit is exactly 5, we always round up to the next hundred. For example, 350 rounds to 400.

How can I practice rounding at home?

You can practice rounding with prices in the supermarket, distances on a map, or any numbers you see around you. Try rounding 347, 682, or 153 to the nearest 100.

Can I round numbers larger than 1000?

Yes! You can round any number to the nearest 100. For example, 1567 rounds to 1600, and 2431 rounds to 2400.