Would it be correct to say that for 2009 to be a base <b>M </b> number, <b>M</b> would have to be > 9 because any base <= 9 could not have a digit "9" in it?
Assuming that each digit in "2009" represents a multiplier of a different power of <b>M</b>, to get the decimal equivalent one must evaluate: 2*M^3 + 0*M^2 + 0*M^1 + 9*M^0 = 2*M^3 + 9