Watch out
Subtracting the percentage from the final value.
Scottish National 5 Mathematics
National 5 Maths Reverse percentages
Find an original quantity before a percentage increase or decrease.
Formula reference
Check the National 5 rules and formulae linked to this topic.
Which method?
Match exam clues to a suitable method.
Before you start
- Convert the percentage change to a multiplier.
- Store the full multiplier calculation and round money only at the final answer.
- Read the command word, record the units or requested form, and make the final answer match it.
Explanation
Reverse percentages is an assessed part of Scottish National 5 Mathematics in the number area. Find an original quantity before a percentage increase or decrease.
Convert the percentage change to a multiplier.
Divide the final value by that multiplier.
Check by applying the percentage change to the original value.
The interactive bank below mixes direct skills, reverse questions, interpretation and contextual reasoning rather than repeating one number pattern.
Key formulae and rules
- original value = final value / multiplier
Check
Apply the multiplier to your original value; it should reproduce the stated final value before rounding.
Exam tip
Show the number rule or multiplier used, retain exact values where requested and round only once at the end.
Calculator tip
Store the full multiplier calculation and round money only at the final answer.
Worked examples
Worked example 1
Reverse percentages worked example
A price after a 20% increase is £84. Find the original price.
- A 20% increase has multiplier 1.2.
- = 70
Answer: £70
Watch out
- Subtracting the percentage from the final value.
- Dividing by 20 instead of by 1.2.