The parsing process is as follows:

Fold 1 time to get 1 = 2 1- 1 crease;

Fold twice to get1+2 = 3 = 2 2-1crease;

Fold it in half for three times, and you can get 3+2 2 = 7 = 2 3- 1 crease;

Fold it in half for 4 times, and you can get 7+2 3 = 15 = 2 4- 1 crease;

Fold it in half for 5 times, and you can get15+2 4 = 31= 2 5-1crease.

……

So a piece of paper, folded n times, can get 2 n- 1 crease.

This problem mainly investigates mathematical induction.

Extended data:

Mathematical induction is to prove that any given situation is correct in different ways (first, second, third, all the time).

The simplest and most common mathematical induction is to prove that a proposition holds when n is equal to any natural number. Proof is divided into the following two steps:

1. Prove that the proposition holds when n= 1.

2. Assuming that the proposition holds when n=m, it can be deduced that the proposition also holds when n=m+ 1. (m stands for any natural number).

The principle of this method lies in: first, prove that the proposition is valid at a certain initial value, and then prove that the process from one value to the next is valid. When these two points are proved, then any value can be deduced by repeatedly using this method.