Find percentages of a quantity - Find 10%
Theory
To find 10% of a quantity, divide it by \(10\), because \(10\%\) is one tenth of the whole. Once you know \(10\%\), you can build \(20\%\) and \(30\%\) by multiplying.
Per cent means out of \(100\), so \(10\% = \dfrac{10}{100} = \dfrac{1}{10}\).
Finding one tenth of a quantity means dividing it by 10.
Once you know \(10\%\), build others: \(20\%\) is two tenths and \(30\%\) is three tenths.
Divide the quantity by \(10\) to find \(10\%\).
| Quantity | Divide by 10 | 10% is |
|---|---|---|
| $200 | \(200 \div 10\) | $20 |
| \(80\) | \(80 \div 10\) | \(8\) |
| \(35\) | \(35 \div 10\) | \(3.5\) |
How to find 10% of a quantity
- Divide the quantity by \(10\).
- Keep a decimal answer if the amount does not divide evenly.
- Multiply to build bigger percentages: \(20\%\) is two lots of \(10\%\).
10% is one tenth, so divide by 10.
| \(200 \div 10\) | \(=\) | \(20\) |
Divide by 10.
| \(80 \div 10\) | \(=\) | \(8\) |
20% is two lots of 10%. First \(40 \div 10 = 4\).
| \(20\%\text{ of }40\) | \(=\) | \(2 \times 4 = 8\) |
The whole is ten times 10%.
| \(12 \times 10\) | \(=\) | \(120\) |
Common pitfalls
Frequently asked questions
How do you find 10% of an amount?
Divide the amount by \(10\), because \(10\%\) is one tenth. \(10\%\) of \(80\) is \(8\).
Why divide by 10 and not subtract 10?
A percentage is a share of the amount, not a fixed number taken away. \(10\%\) of $60 is $6, not $50.
What if 10% is not a whole number?
The answer can be a decimal. \(10\%\) of \(35\) is \(3.5\).
How do you find 20% or 30%?
Find \(10\%\) first, then multiply. \(20\%\) is two lots of \(10\%\), and \(30\%\) is three lots.