I was trying to solve this question from the book Why math by R.D Driver: Imagine a large piece of paper five-thousandths of an inch thick being torn in half, and the two pieces placed one on top of the other. Then these two pieces are torn in half, and the four pieces are put in a stack. This process of tearing in half and stacking is done 25 times. Will the final stack be (a) less than an inch thick, (b) between an inch and a yard thick, or (c) more than a yard thick?
My solution: We start with 5000th of an inch in the first iteration. So in the 2nd iteration, we have 5000th of an inch from 1st half and 5000th of an inch from 2nd half - so total $2/5000th$ of an inch. Similarly, at the end of 25 iterations, we get $33554432/5000th$ of inch, which is 6710.88 inches. But the book says the answer is 2.65 miles.
Can someone please explain this?