reset it to zero and increment the digit just before the 9 so the
number becomes "00010". Leading zeros we don't write except if it is
the only digit (number 0). And of course, we write zeros if they occur
reset it to zero and increment the digit just before the 9 so the
number becomes "00010". Leading zeros we don't write except if it is
the only digit (number 0). And of course, we write zeros if they occur