***November 2013 - Mathematics Level 2***

gcf101
Sun, 03 Nov 2013 19:48:55 +0000

Another approach:
4,XXX,239,040 has to be divisible by 9, therefore the sum of its digits is a multiple of 9 (see [Divisibility Rules](Art of Problem Solving)).

4+2+3+9+0+4+0 = 22, so the remaining 3 digits should add to 5, 14, or 23.



Divisibility Rule for 11 came in handy on one of the recent Math 2s.