11+ Maths: Recognising Percentage Increase and Decrease
21 October 2026
Understanding percentage change
Percentage increase and decrease questions are a common part of 11+ maths. They test your child's ability to spot how much a value has gone up or down, and to express that change as a percentage.
What does percentage increase or decrease mean
A percentage increase shows how much a value has grown compared to its starting point. A percentage decrease shows how much a value has dropped from the original.
How to work out the difference
Start by finding the difference between the two values. Subtract the original value from the new value if you are checking for an increase, or the other way round for a decrease.
Turn the difference into a percentage
Take the difference you have found. Divide it by the original value. Then multiply by 100 to get the percentage change.
Key insight: In 11+ questions, the original value is always the starting point for your percentage calculation. Always divide by the original, not the new value.
Worked example
A jacket costs £50. The price goes up to £60. What is the percentage increase?
Step 1: Find the difference.
£60 - £50 = £10
Step 2: Divide the difference by the original price.
£10 ÷ £50 = 0.2
Step 3: Multiply by 100 to get the percentage.
0.2 × 100 = 20
The correct answer is 20 percent increase.
