- Joined
- Jun 25, 2016

- Messages
- 118

- Reaction score
- 16

I'm trying to apply chads method but i can't tell how. clearly order matters and when order matters he just puts the number of selections on top and thats it because order matters... so it should be 5! but its not..

another one is how many ways can the same 4 physics books, 3 algebra books, and 2 chem books be arranged on a self.. again order matters so it should be 9! ??

i feel like his way isn't applying.

even if i use the equation of n!/(n-r)! there isn't a clear r to plug in!???

pelase help