Question

What should you multiply if you change centimetres to millimetres

Answer 1

10 mm/cm

Explanation:

The conversion factor always has a value of 1. It is a fraction with the numerator equal to the denominator -- only the units are different.

The numerator units are the units you're converting to: millimeters. The denominator units are the units you're converting from: centimeters.

You know that 1 cm = 10 mm, so when you arrange the fraction as described, the conversion factor you're multiplying by is ...

`\boxed{\frac{10\,\text{mm}}{1\,\text{cm}}}`