what is the circumference of 2cm

the circumference of 2cm is a circle with a radius of .32 cm

Dont you use pi in this situation 3.14*2=6.28?

the reason that your question did not get answered earlier is that you did not specify what 2cm was.

Is it the distance from the centre to the circumference which is called the radius.

Or is it the distance all the way across which is called the diameter.

In his answer Zegroes has assumed it its the diameter.

C = pi * diameter.

C=pi*2

$${\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}} = {\mathtt{6.283\: \!185\: \!307\: \!179\: \!586\: \!5}}$$

C=6.28cm correct to 2 decimal places.