If you need to convert a fraction to a decimal, simply divide the denominator of the fraction into the numerator. If both the numerator and denominator are even, then you'll be able to convert the fraction into a non-repeating number. Otherwise you cannot fully divide the denominator into the numerator, and you have to indicate that the resulting decimal point is a repeating decimal.
To change a decimal into a fraction, the numbers to the right of the decimal place make up the numerator of the resulting fraction. Count the number of decimal places to the right of the decimal place. If there are two decimal places to the right of the decimal place, then create the fraction by placing the numbers to the right of the decimal place over 100. If there are three decimal places to the right of the decimal place, create the fraction by placing the numbers to the right of the decimal place over 1000.