A woman labels the squares of a very large chessboard 1 through 64. On each square k, the woman puts 2^k grains of rice. How many more grains of rice are placed on the 10th square than on the first 9 squares combined?
+191 1024 is 1 more than 512+256+128+64+32+16+8+4+2+1.
It's helpful to notice that every term is 1 more than all the previous terms combined.
