# Length conversion problems involving millimetres and metres.

A millimetre is about the thickness of 10 sheets of paper and a metre is about the average height of an emperor penguin. A metre is equivalent to one thousand millimetres (1m = 1000mm). Therefore, if you are converting a length from metres into millimetres all you need to do is multiply the number by 1000. Likewise, if you are converting millimetres into metres, then all you need to do is divide your number by 1000.

Let’s take a look at some questions on converting between millimetres and metres.

**Example 1**

A doorway has a height of 2 metres. What is the height of the door in millimetres?

All you need to do here is multiply 2 by 1000 as you converting metres to millimetres.

2 × 1000 = 2000mm

**Example 2**

A toy train is 800mm in length. Convert this length into metres.

This time you are converting millimetres into metres so you need to divide by 1000.

Therefore, 800 ÷ 1000 = 0.8m

**Example 3**

A car has a length of 3.67 metres. Work out the length of the car in millimetres.

Like example 1, you are converting metres into millimetres. Therefore, you need to multiply 3.67 by 1000.

3.67 × 1000 = 3670 mm

**Example 4**

A rectangle is 657mm in length and 451mm wide. What is the perimeter of the rectangle in metres?

To work out the perimeter of a rectangle, all you need to do is add up all of the side lengths.

657 + 657 + 451 + 451 = 2216mm.

Next, change this answer into metres by dividing 2216 by 1000.

2216 ÷ 1000 = 2.216m