The fraction 3/8 written in decimal form is 0.375. According to Syracuse University, converting a fraction to a decimal involves dividing the part on the top of the fraction (the numerator) by the part on the bottom (the denominator). In this case, three is divided by eight.
The reverse process is a little more difficult. To convert a decimal to a fraction, first put the decimal over the number one and then move both numbers to the right until the decimal point is gone. For this example, 0.375 over one becomes 375 over 1,000, because the decimal is moved to the right three places.
If necessary, the expression is simplified by finding the largest number that divides into both the top and the bottom. In the fraction 375/1,000, both parts can be divided by 125 to give 3/8, the original fraction.