$$18$$ is divisible by both $$2$$ and $$3$$. It is also divisible by $$2\times 3=6$$. Similarly, a number is divisible by both $$4$$ and $$6$$. Can we say that the number must also be divisible by $$4\times 6=24$$? If not, give an example to justify your answer.
No.
It is not necessary because $$12$$ and $$36$$ are divisible by $$4$$ and $$6$$ both, but are not divisible by $$24$$.