You'll divide 3 by 5 and put the minus sign if you have a calculator
If you don't:
3 divided by 5 is impossible since 3 is smaller than 5. So you write 0 somewhere. [0]
Then you add put a 0 beside the 3 to make it 30 and when you do that, you add a decimal point (.) to the 0 you've wrote somewhere[0.]. Then you can now divide 30 by 5 to give you 6, then you put the 6 after the decimal point to give you [0.6].