**Definitions:**

**Millimeter** (abbreviation: **mm**): is a unit of length in the SI metric system, equal to one thousandth of a metre. Therefore, there are thousand millimetres in a metre and ten millimetres in a centimetre.

**Kilometer** (abbreviation: **km**): is a unit of length in the SI metric system, equal to one thousand metres (kilo- being the prefix for 1000). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world countries.

## How to Convert Millimeters to Kilometers

*Example: How many kilometers are equivalent to 31.3 millimeters?*

As;

1 millimeters = 1.0E-6 kilometers

31.3 millimeters = Y kilometers

Assuming Y is the answer, and by criss-cross principle;

Y equals 31.3 times 1.0E-6 over 1

(i.e.) Y = 31.3 * 1.0E-6 / 1 = 3.13E-5 kilometers

Answer is: 3.13E-5 kilometers are equivalent to 31.3 millimeters.

*Practice Question: Convert the following units into km:*

N.B.: After working out the answer to each of the next questions, click adjacent button to see the correct answer.

( i ) 89.59 mm

( ii ) 72.89 mm

( iii ) 81.41 mm