Let's recap some helpful facts that will help us to convert fractions.
A thousandth is a tenth of a hundredth.
So 10 thousandths make 1 hundredth.
A hundredth is a tenth of a tenth.
So 10 hundredths make 1 tenth.
And 100 thousandths make 1 tenth too.
Using this knowledge, we can then say,
4/100 = 40/1000
3/10 = 300/1000
850/1000 = 85/100