# Divide Decimals

## Dividing Decimals by Powers of Ten:

If you **divide** a decimal number **by 10**, the decimal point moves **1 place** to make the number **smaller**

(for example 2345.6 ÷ 10 = 234.56).

If you **divide** a decimal number **by 100**, the decimal point moves **2 places** to make the number **smaller**

(for example 2345.6 ÷ 100 = 23.456).

If you **divide** a decimal number **by 1000**, the decimal point moves **3 places** to make the number **smaller**

(for example 2345.6 ÷ 1000 = 2.3456).

## Dividing Decimals by Other Whole Numbers:

## Example One - Price of Strawberries

**3 kilograms of strawberries cost $19.65**. What is the price of **one kilogram**?

**Answer:**

$19.65 ÷ 3 = $6.55

## Questions - Price of Food

**Q1.** A dozen eggs (12 eggs) cost $5.16. What is the price of one egg?
**Q2.** 10 apples cost $4.90. What is the cost of one apple?
**Q3.** 5 bags of Persian Cotton Candy cost $24.25. What does one bag cost?

**Answers**
**A1.** 43 cents
**A2.** 49 cents
**A3.** $4.85

## Dividing Decimals by Decimals:

## Example Two - Injection Doses

A glass **vial contains 45.5 millilitres** of medicine. Each **injection requires 0.5 millilitres**. How many injections can be given from one glass vial?

**Answer:**

= | 45.5 |

0.5 |

= | 455 | (Multiply both the numerator and the denominator by 10 to get rid of the decimal in the denominator.) |

5 |

= 91 injections

## Example Three - Smaller Injection Doses

Using the same-sized glass **vial containing 45.5 millilitres** of medicine, each **injection has 0.05 millilitres**. How many injections can be given from one glass vial?

**Answer:**

= | 45.5 |

0.05 |

= | 4550 | (Multiply both the numerator and the denominator by 100 to get rid of the decimal in the denominator.) |

5 |

= 910 injections

## Question - Ringtone Download

To download my favourite ringtones to my mobile 'phone costs $0.90 each. How many ringtones can I download if I have:

(a) $46.80

(b) $10.80

(c) $20.70?

**Answers**

(a) 52

(b) 12

(c) 23

## Maths Fun - Dividing by Zero

Try dividing any number by zero on your calculator. The calculator will display and "Error" message because dividing by zero
is **impossible**. However, we can **approximate** what number we could get if we divided a number such as "8" by numbers that are **close to zero**.

Use your calculator to work out the following:

- 8 ÷ 1
- 8 ÷ 0.1
- 8 ÷ 0.01
- 8 ÷ 0.001
- 8 ÷ 0.0001
- 8 ÷ 0.000000000000000000000000000000000001

What do you notice?