Question

http://img14.imageshack.us/img14/4914/r9l1.png

Answer 1

I think drawing a tree helps here.

Answer 2

I think the answer is 3^4, or 81. Anyone get anything else?

Answer 3

say the required number of disks = \(x \)

disks left after First iteration : \(\large x - \frac{x}{3} = \frac{2x}{3}\)

disks left after Second iteration : \(\large \frac{2x}{3} - \frac{2x}{9} = \frac{4x}{9} = (\frac{2}{3})^2 x\)

....

disks left after Fourth iteration : \(\large (\frac{2}{3})^4 x\)

Answer 4

this number must be an integer ok

Answer 5

since 3^4 does not go in 2^4,
3^4 must divide x

so the minimum value for x is 3^4