Move the decimal point one place
To find 10% of a number, move the decimal point one place to the left. 10% of 60 is 6. 10% of 48 is 4.8.
Every other percentage is built from that piece. 30% is three of them. 5% is half of one.
Add the pieces you need
35% of 60
= 10% + 10% + 10% + 5%
= 6 + 6 + 6 + 3
= 21
Three whole blocks of 10%, then half a block for the last 5%.
The two numbers can also swap places. 4% of 75 is awkward to build, but 75% of 4 is three quarters of 4, which is 3. Both come to 4 × 75 ÷ 100.
The 5% piece is half of the 10% piece, not the number 5. Half of 6 is 3, so the last piece adds 3.
Work out a tip
A bill comes to 48, and you want to leave 15%.
Find 10% of 48 first, then add half of that.
Try it
What is 15% of 48?
- 7.20
- 9.80
Show the answer
7.20
10% of 48 is 4.80, and half of that is 2.40. The two pieces together make 7.20.
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