Question

How many m are in 300 mm

Answer 1

0.3 because when you move your decimal point you have to move it 3 times then you add your zero and you get 0.3

Answer 2

There are 1,000 mm in a m. So with that said you would do 300/1000. This equals 0.3. 
So your answer is going to be 0.3
Hope this helps :)