**Problem: **

Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner.

How many such routes are there through a 20×20 grid?

**My Solution:**

from scipy.special import comb # This solution uses combinatoric approach # the idea is we must make 40 moves in total, 20 of which must be down. # How many ways to do that? well 40 choose 20. print (comb(40,20))