0.38 would be equal to 38/100. There are two zeros, so you move the decimal over twice.
When you see 3/8, you should think 3 divided by 8.
To solve this without a calculator, divide .8 into 3 and move the decimal place.
0.8 * 3 = 2.4
This is close, but not quite 3. 2.4 is 0.6 away from 3. 0.6 is 75%, or 0.75, of 0.8. Or you could look at it as 6/8 = 3/4 = 75/100 = 75%
3/0.8 = 3.75
We determined the 3 because 0.8 *3 is the highest whole number we can multiply by before surpassing our goal of 3.
We determined the 0.75 because we could only add 0.6 to get to our goal of 3 instead of 0.8, and 0.6 is 75%, or 0.75, of 0.8.
Now move the decimal place back over to the right by one since we removed a decimal from 0.8, making it 8 again.
3/8 = 0.375