Thanks for your replies guys.
In this case:
True or False:
If ab Ξ 0 (mod 11) then a Ξ 0 (mod 11) or b Ξ 0 (mod 11). Explain your answer.
You would agree that the example:
If a=5.5 and b=2. Clearly ab is congruent to 0 modulo 11, but neither a or b is congruent to 0 modulo 11. Hence this is False.
This would indicate that it is also false.
I am not missing anything here am I???