I am trying to count the number of ways to play 4 indistinguishable objects in 6 bins. Each bin can contain either 0 or 1 object. We can think of this as the number of binary strings of length 6 with exactly four 1's. Thanks!
Let me draw you 6 bins:
now let me give you an example:
and another example:
and another example
in how many ways can you put those x in 6 bins?
Let me sharpen the question: in how many ways can you choose 4 items from 6? and here's another nice thing to notice...in how many ways can you choose 2 from 6? (hint: same answer)