Fifth Sylow Theorem

Theorem
The number of Sylow $p$-subgroups of a finite group is a divisor of their common index.

Also known as
Some sources call this the fourth Sylow theorem and merge it with what we call the Fourth Sylow Theorem.

Others merge this result with what we call the Fourth Sylow Theorem and call it the third Sylow theorem.

Others merge this with what we call the Third Sylow Theorem and call it the third Sylow theorem.

Also see

 * Sylow Theorems