guess in 4^5 ways.
Your answer is correct. I got 5x4x3x2. The way I figure is, the 1st finger can have any of the 5 rings. So 5 ways for 1st finger. The 2nd finger can have any of the 4 remaining rings. So 4 ways for 2nd finger and .....
Why is my answer incorrect?
You forget that any of 4 fingers can have all the rings.
The way it works here, take one ring, on how many fingers it can be worn? - 4
take another ring - 4, and so on
so you get 4*4*4*4*4 = 4^5