Write down the decimal figure.
Write the number to the left of the decimal (if a number is present in this position) as the whole number within the fraction. For example, 3.45 would start out as 3; a fraction will follow. If there is a zero to the left of the decimal, there will be no whole number in the fraction.
Write the numbers to the right of the decimal as the numerator (top number) in a fraction. Drop the decimal. For example, in the conversion of 3.45, the numerator would be 45.
Write the number 1 in the denominator of the fraction, followed by a series of zeros. You determine how many zeros to add by counting how many numbers were present on the right side of the decimal. In this example (3.45), there are two numbers to the right of the decimal, so you would add two zeros to the 1 to create the final answer: 3 45/100. This shows the place values used in the original decimal.