title: how to generate longer random number from a short random number?
body: <p>I have a short random number input, let's say int 0-999.</p>
  
  <p>I don't know the distribution of the input. Now I want to generate a random number in range 0-99999 based on the input without changing the distribution shape.
  I know there is a way to make the input to [0,1] by dividing it by 999 and then multiple 99999 to get the result. However, this method doesn't cover all the possible values, like 99999 will never get hit.</p>