#### Rules for Finding Basic Percentages

- To find 1%, divide the number by 100.
- To find 5%, divide the number by 20 or find half of 10%.
- To find 10%, divide the number by 10.
- To find 20%, divide the number by 5 or find 10% and double it.
- To find 25%, divide the number by 4.
- To find 33.̄3%, divide the number by 3.
- To find 50%, divide the number by 2.
- To find 75%, divide the number by 4 and then multiply by 3.

**Find simple percentages of a number by dividing using the rules shown above.**

- We want to find 20% of 40.
- To find 20% of a number, divide the number by 5 or find 10% and double it.
- 40 Ã· 5 = 8 and so, 20% of 40 = 8.
- Alternatively, we can find 10% and double it.
- To find 10% of 40, divide it by 10.
- 10% of 40 = 4.
- We double 10% to find that 20% = 8.

#### Teaching and Introducing Simple Percentages

#### Finding Simple Percentages: 10%, 25%, 50% and 100%

#### Finding Simple Percentages: 1%, 5%, 20% and 75%

#### Finding Multiples of 10%

#### Calculating Simple Percentages (1%, 5%, 20% and 75%): Interactive Activity

1%, 5%, 20% and 75% of an Amount: Interactive Questions

#### Calculating Simple Percentages (10%, 25% and 50%) : Interactive Activity

Finding 10%, 25% and 50% of an Amount: Interactive Questions

#### Calculating Multiples of 10% of an Amount

Multiples of 10 Percent: Interactive Questions

#### Simple Percentages as Fractions Worksheets and Answers

#### Simple Fractions of Amounts Worksheets and Answers

#### Finding Multiples of 10% of a Number Worksheets and Answers

# Simple Percentages of Amounts

## Rules for Finding Simple Percentages of a Number

**The rules for finding simple percentages of a number are shown in the following table:
**

**
**

Percentage | Rule |
---|---|

1% | Ã· 100 |

5% | Ã· 20 |

10% | Ã· 10 |

20% | Ã· 5 |

25% | Ã· 4 |

33.̄3% | Ã· 100 |

50% | Ã· 2 |

75% | Ã· 4 then Ã— 3 |

To find the percentages of a number shown in the table above, simply divide the number using the rules provided.

Simple percentages are percentages of amounts that can be found with a simple division or multiplication. They do not require any addition of any smaller percentages.

For example, 50% is a simple percentage because we simply divide by 2 to find it. 31% is not a simple percentage we would need to calculate 30% and 1% and add them together.

Here is a poster showing how to calculate basic percentages.

To introduce percentages, it is best to start with simple percentages and showing them as a fraction out of 100. For example, 50% means 50 out of 100, which is half. To find 50% of a number, simply half it.

Before looking at larger percentages, it is best to introduce basic percentages with a visual guide to how large they are. To teach how large a percentage is, you can show the percentage as a fraction of 100 squares.

Start by introducing the following percentages first: 10%, 20%, 25%, 50%, 75% and 100%.

## How to Calculate 1% of a Number

**To calculate 1% of a number, divide the number by 100. To divide by 100, move the decimal point two places left. For example, 1% of 135.6 = 1.356.**

1% means 1 out of 100. 1% is the same as the fraction ^{1}/_{100} .

To teach 1%, we can show 1 square shaded out of 100 squares.

1% means ^{1}/_{100} and so, finding 1% of a number means to find ^{1}/_{100} of that number.

To find 1% of a number without a calculator, divide the number by 100. The easiest way to do this is to move the decimal point 2 places to the left.

Here are some examples of finding 1%,

Question | Answer |
---|---|

1% of 300 | 3 |

1% of 150 | 1.5 |

1% of 25 | 0.25 |

1% of 8 | 0.08 |

1% of 3.6 | 0.036 |

1% of 0.205 | 0.00205 |

**To find 1% of a number with a calculator, divide the number by 100. You can also multiply the number by 0.01.**

1% is a basic percentage because it can be found with one simple division. 1% is a very useful percentage to know how to find because you can use it to find any larger, whole number percentage of a number. Simply multiply the percentage required by the value of 1%.

## How to Calculate 5% of a Number

**To find 5% of a number, divide the number by 20. This can be done by dividing the number by 10 and then halving it. For example, 5% of 40 = 2.**

5% means 5 out of 100. 5% is the same as the fraction ^{5}/_{100} , which can be simplified to ^{1}/_{20} .

5% is a twentieth of the whole number.

5% means ^{1}/_{20} and so, finding 5% of a number means to find ^{1}/_{20} of that number.

To find 5% of a number without a calculator, divide the number by 20. The easiest way to do this is to divide by 10 and then halve the result.

Here are some examples of finding 5%,

Question | Answer |
---|---|

5% of 200 | 10 |

5% of 60 | 3 |

5% of 30 | 1.5 |

5% of 8 | 0.4 |

5% of 1.6 | 0.08 |

5% of 0.402 | 0.0201 |

**To find 5% of a number with a calculator, divide the number by 20. You can also multiply the number by 0.05.**

Finding 5% is best to introduce after you have already learnt how to find 10%.

## How to Calculate 10% of a Number

**To calculate 10% of a number, divide the number by 10. The easiest way to do this is to move the decimal point one place to the left. For example, 10% of 14.5 = 1.45.**

10% means 10 out of 100. 10% is the same as the fraction ^{10}/_{100} , which simplfies to ^{1}/_{10} .

To teach 10%, we can show 10 squares shaded out of 100 squares.

10% means ^{1}/_{10} and so, finding 10% of a number means to find ^{1}/_{10} of that number.

To find 10% of a number without a calculator, divide the number by 10. The easiest way to do this is to move the decimal point 1 place to the left.

Here are some examples of finding 10%,

Question | Answer |
---|---|

10% of 1200 | 120 |

10% of 600 | 60 |

10% of 50 | 5 |

10% of 9 | 0.9 |

10% of 5.3 | 0.53 |

10% of 0.105 | 0.0105 |

**To find 10% of a number with a calculator, divide the number by 10. You can also multiply the number by 0.1.**

10% is a basic percentage because it can be found with one simple division. 10% is a very useful percentage to know how to find because we can easily multiply 10% to find other multiples of 10%, such as 20%, 30% etc.

## Multiples of 10% of a Number

**To find multiples of 10% of a number, use these rules:
**

**
**

Percentage | Rule |
---|---|

10% | Ã· 10 |

20% | Ã· 10 then Ã— 2 |

30% | Ã· 10 then Ã— 3 |

40% | Ã· 10 then Ã— 4 |

50% | Ã· 10 then Ã— 5 |

60% | Ã· 10 then Ã— 6 |

70% | Ã· 10 then Ã— 7 |

80% | Ã· 10 then Ã— 8 |

90% | Ã· 10 then Ã— 9 |

Here is a poster showing how to find all of the multiples of 10% of a number.

For example, to find 30% of 50, divide 50 by 10 to find 10% and then multiply this by 3 to get 30%.

To find 10% of 50, divide it by 10. 10% of 50 = 5.

Now that we have 10%, we simply multiply it by 3 to find 30%. 30% of 50 = 15.

Here is another example of finding a multiple of 10 percent. What is 40% of 70 grams?

To find 40% of a number, divide it by 10 to find 10% and then multiply this by 4.

10% of 70 grams = 7 grams.

To find 40%, we multiply 10% by 4. 40% of 70 grams = 28 grams.

Here we will find 80% of 120.

To calculate 80% of a number, divide the number by 10 to get 10% and then multiply this by 8.

10% of 120 = 12.

80% is 10% multiplied by 8. 80% = 96, therefore 80% of 120 = 96.

## How to Calculate 20% of a Number

**To calculate 20% of a number, divide it by 5. Alternatively, divide the number by 10 and then double it. For example, 20% of 30 = 6.**

20% means 20 out of 100. 20% is the same as the fraction ^{20}/_{100} , which can be simplified to ^{1}/_{5} .

20% is a fifth of the whole number.

20% means ^{1}/_{5} and so, finding 20% of a number means to find ^{1}/_{5} of that number.

To find 20% of a number without a calculator, divide the number by 5. Alternatively, divide the number by 10 and then double it.

Here are some examples of finding 20%,

Question | Answer |
---|---|

20% of 400 | 80 |

20% of 20 | 4 |

20% of 70 | 14 |

20% of 5 | 1 |

20% of 6.1 | 1.22 |

20% of 0.303 | 0.0606 |

**To find 20% of a number with a calculator, divide the number by 5. You can also multiply the number by 0.2.**

## How to Calculate 33 ^{1}/_{3} % of a Number

**To calculate 33 ^{1}/_{3} % of a number, divide it by 3.
**

**
3 ^{1}/_{3} is the same as 33.̄3%. To find 3 ^{1}/_{3} or 33.̄3%, divide the number by 3.**

33.̄3% means ^{1}/_{3} and so, finding 33.̄3% of a number means to find ^{1}/_{3} of that number.

To find 33.̄3% of a number without a calculator, divide the number by 3.

**To find 33.̄3% of a number with a calculator, divide the number by 3. You can also multiply the number by 0.̄3.**

## How to Calculate 50% of a Number

**To calculate 50% of a number, divide the number by 2. For example, 50% of 20 = 10.**

50% means 50 out of 100. 50% is the same as the fraction ^{50}/_{100} , which simplfies to ^{1}/_{2} .

To teach 50%, we can show 50 squares shaded out of 100 squares.

50% means ^{1}/_{2} and so, finding 50% of a number means to find ^{1}/_{2} of that number.

To find 50% of a number without a calculator, divide the number by 2. To divide an odd number by 2, subtract one, half it and then add 0.5

Here are some examples of finding 50%,

Question | Answer |
---|---|

50% of 800 | 400 |

50% of 300 | 150 |

50% of 20 | 10 |

50% of 7 | 3.5 |

50% of 2.6 | 1.3 |

50% of 0.804 | 0.402 |

**To find 50% of a number with a calculator, divide the number by 2. You can also multiply the number by 0.5.**

## How to Calculate 75% of a Number

**To calculate 75% of a number, divide the number by 4 and then multiply this result by 3. For example 75% of 20 = 15.**

75% means 75 out of 100. 75% is the same as the fraction ^{75}/_{100} , which simplfies to ^{3}/_{4} .

75% is three quarters of an amount.

To teach 75%, we can show 75 squares shaded out of 100 squares. It is helpful to shade the squares in the four corners as shown.

75% means ^{3}/_{4} and so, finding 75% of a number means to find ^{3}/_{4} of that number.

To find 75% of a number without a calculator, divide the number by 4 and then multiply by 3.

Here are some examples of finding 75%,

Question | Answer |
---|---|

75% of 800 | 600 |

75% of 300 | 225 |

75% of 60 | 45 |

75% of 4 | 3 |

75% of 6.8 | 5.1 |

75% of 0.334 | 0.2505 |

**To find 75% of a number with a calculator, divide the number by 4 and then multiply by 3. You can also multiply the number by 0.75.**

## What is 100% of a Number?

**100% of a number is the whole of the number. 100% means one whole and so, 100% of a number is simply the number itself.**

100% means 100 out of 100. 100% is the same as the fraction ^{100}/_{100} , which simplfies to 1 whole.

We can see in this diagram that 100% shows all 100 squares shaded in.

To find 100% of something simply means to find the whole amount of it. For example, 100% of 25 = 25.

Now try our lesson on *How to Calculate Percentages of Numbers* where we learn how to find any percentage of a number.