What is 9 mm in cm?

Answer 1

You will be better served if you learn to do unit conversions in general. All it takes is to multiply your starting value by a fraction formed by the unit conversion. In this case, the conversion is that 1 cm = 10 mm. You can make two different fractions: 1 cm/10 mm = 1 or 10 mm/1 cm = 1. Multiply by the form that will divide out the unit you are trying to eliminate.

In this case:
9 mm x (1cm/10 mm) = 9x1/10 cm = 9/10 cm = 0.9 cm

This type of operation is very easy and very routine.

Answer 2

0.9 centimetres

Answer 3

1 cm = 10 mm, 9 mm = 0.9 cm