**Definitions:**

**Inch** (abbreviation: **in**): is a unit of length in the (British) imperial and United States customary systems of measurement now formally equal to 1/36 yard but usually taken as 1/12 of a foot.

**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.

## How to Convert Inches to Millimeters

*Example: How many millimeters are equivalent to 89.1 inches?*

As;

1 inches = 25.4 millimeters

89.1 inches = Y millimeters

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

Y equals 89.1 times 25.4 over 1

(i.e.) Y = 89.1 * 25.4 / 1 = 2263.14 millimeters

Answer is: 2263.14 millimeters are equivalent to 89.1 inches.

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

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

( i ) 63.58 in

( ii ) 69.99 in

( iii ) 0.46 in