To convert a repeating decimal to a fraction, let N be the number, and let n be the number of digits in the repeating block. For example,

has 2 digits in the repeating block, whereas

has only 1.
Setting N equal to its value, multiply both sides of the equation by 10n. Then subtract N from both sides. You will end up with an equation which you can solve for N as a fractional value.
Example:
Convert the decimal

into a fraction.
Start with the equation:

There are two digits in the repeating block, so multiply both sides by 102 = 100.
Now subtract N from both sides. Notice that the repeating part cancels out.
Divide both sides by 99, multiply numerator and denominator by a power of 10 to get rid of the decimal point, and simplify.