Add 10 or 100 to a Three-Digit Number: Step-by-Step Example
30 October 2026
Adding 10 or 100 to a three-digit number is a key skill for mental maths. It helps children spot patterns in numbers and understand place value.
Worked example
Add 100 to 286
Look at the hundreds digit in 286. It is 2.
Add 1 to the hundreds digit because 100 is one group of one hundred.
The hundreds digit becomes 3. The number is now 386.
The answer is 386.
Key insight: When you add 100, only the hundreds digit changes. Your child will now recognise this pattern and be ready to practise similar questions with confidence.
