Need explanataion to this Math question from gre week 1

[rashneetforsampleapp]

If the expression 1000! / 77^ x
​ results in an integer, what is the largest possible value of x?

the answer is 48 but im not sure how, can someone please explain?

[Leaderboard]

How to Ask Better GRE Questions on Forums

Since GregMat (who is a very chill person) doesn’t have any specific formatting rules when it comes to asking questions on the forums, I feel like there should at least be a reference text of some sort that can help people ask better questions and make the process more enjoyable for those who try to answer them. The Golden Rule: Imagine You’re Trying To Answer the Question Before you post your question about GRE preparation, practice questions, or strategies, try to put yourself in the shoes of…

[margot.e.shumway]

Which video or quiz is this from?

[tushar.minj]

I think the answer is 98?