#3
Top 50 Mistake
Dividing by one ratio part instead of the total
"The Part-Total Mixup"
The Mistake in Action
Share £60 in the ratio 2 : 3
Wrong:
- $60 \div 2 = 30$
- $60 \div 3 = 20$
- Shares are £30 and £20
Why It Happens
Students divide the total by each individual ratio number rather than finding the total number of parts first.
The Fix
Always find the TOTAL parts first.
The ratio 2 : 3 means there are $2 + 3 = 5$ parts in total.
Then:
- One part = $60 \div 5 = £12$
- First share = $2 \times 12 = £24$
- Second share = $3 \times 12 = £36$
Check: $24 + 36 = 60$ ✓
Spot the Mistake
Can you identify where this student went wrong?
Share £60 in the ratio 2 : 3
$60 \div 2 = 30$
$60 \div 3 = 20$
Shares are £30 and £20
Click on the line that contains the error.
Related Topics
Learn more about the underlying maths: