Suppose, for example, that you are asked to figure out the number
of customers that your railroad will have at a given time if the
number of customers doubles each month starting now. Plainly,
the number after *n* months is proportional to *2 ^{n}*,
thus requiring you to develop a function that computes the

One way to do the computation is to count down the parameter, `n`

, to
`0`

, multiplying a variable, `result`

, whose initial value is 1,
by 2 each time that you decrement `n`

:

int power_of_2 (int n) { int result = 1; // Initial value is 1 while (n != 0) { result = 2 * result; // Multiplied by 2 n times n = n - 1; } return result; }