Percentage increase: stopping at the increase
Your child works out the increase correctly and writes it as the final answer, when the question asked for the new price. The working earns method marks, but the answer mark is lost. It happens just as often with discounts, where the child gives the discount instead of the price paid.
What it looks like
A bicycle cost $240. Its price was increased by 15%. What was the new price of the bicycle?
- Increase: 15% × $240 = 15/100 × $240 = $36
- New price: $240 + $36 = $276
Why $36 is wrong: The increase was given as the answer instead of being added to the original price.
Why children do it
- Finding the increase feels like the hard step, so finishing it feels like finishing the question.
- Children read "increased by 15%" and remember the 15%, not what the question asks for at the end.
- Many textbook exercises ask only for the increase, so stopping there is a familiar ending.
How to fix it at home
- Before starting, ask your child to circle the last sentence of the question, which says what to find.
- After every answer, have your child reread the circled words and check the answer matches them.
- Show the shortcut: a 15% increase makes the new price 115% of the old, so $240 × 115/100 = $276 in one step.
- Mix increase, decrease and "how much more" questions so your child must read each one to the end.
Questions parents ask
Does my child lose all the marks for this?
Usually not all. Markers often give a method mark for the correct increase, but the answer mark is lost, and in a 2-mark question that is half the marks.
Is the 115% method better?
It is shorter and it removes the chance to stop early, but only once your child understands why 100% + 15% = 115%.
Where it shows up
Other careless mistakes
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