How to explain subtract a multiple of 100 from a three-digit number in mental addition & subtraction to your student: Example question
30 October 2026
When your child is learning to subtract a multiple of 100 from a three-digit number, it helps to break the process into clear, simple steps. This example shows exactly how to approach these questions using mental maths.
Example question
Subtract 400 from 825.
Step 1: Look at the hundreds digit in 825. It is 8 (which means 800).
Step 2: Subtract 4 hundreds (400) from 8 hundreds.
8 hundreds − 4 hundreds = 4 hundreds.
Step 3: The tens digit is 2 and the ones digit is 5. Keep them the same.
Step 4: Put the digits together.
4 hundreds, 2 tens, and 5 ones make 425.
Answer: 825 − 400 = 425
After working through this example, your child will spot the pattern in subtracting hundreds from a three-digit number. They can now try similar questions and build confidence with this useful mental maths skill.
