If zeros preceed the repeating decimal:
  0.033333333... = 3/90
  0.00073737373... = 73/99000
  0.00174174174... = 174/99900
Zeros in the denominator correspond to zeros before the repeating decimal.

To convert a decimal that begins with a non-repeating part:
For example, to convert the number 0.21456456456456456... to a fraction, write it as the sum of the non-repeating part and the repeating part.
  0.21 + 0.00456456456456456...
Next, convert each of these decimals to fractions. The first decimal has a divisor of power ten. The second decimal (which repeats) is converted according to the pattern above.
  21/100 + 456/99900
Common denominators
  20979/99900 + 456/99900
Sum
  21435/99900
Simplify
  1429/6660 = 0.2145645645...