Number of (non-prime) numbers in a factorial

[user3795]

Hi all, I just watched the “# of Numbers in Factorials II” from the I’m overwhelmed module 1 part 4.
I can’t figure out why they need to divide by 3 at the end for the last example to figure out the number of 24s in 517!, instead of just using the number of 11s (514). BUT when figuring out the number of 77s in 3020! they don’t need to divide by 7 - they just use then number of 11s as if it is the same as the number of 77s.

Why is it different for the two?

[cylverixxx]

You need 3 copies of 2’s in each 24, so if you count the total number of 2’s then dividing by 3 gets you how many 24’s you can make with the 2’s alone, no?

You only need one copy of 11 for each 77, so that’s why you don’t divide by anything.