"x+y divides (100*x + y) whenever, (x+y) divides 99" can be rephrased as "if (x+y) divides 99, then x+y divides (100*x + y)". This is in fact, true.
However, the converse is not true. The error is in assuming that the converse of a true conditional must also be true.
Posted by Charlie
on 2012-05-09 13:40:51