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**Sillysidley** · 11-04-2007

Using properties for divisibilities by 9 and 11, we determine
a+b is 6 mod 9
b-a is 4 mod 11.
Since they are digits, b-a is 4.

11-04-2007	#77
Sillysidley Join Date: Oct 2006 Posts: 822	Using properties for divisibilities by 9 and 11, we determine a+b is 6 mod 9 b-a is 4 mod 11. Since they are digits, b-a is 4. __________________ .