There are 8 rows and 8 columns, or 64 squares on a chessboard. suppose you place 1 penny on row 1 column a, 2 pennies on row 1 column b, 4 pennies on row 1 column c, and so on … estimate: how many pennies in row 1? pennies estimate: how many pennies in rows 1-4? pennies estimate: how many pennies on the entire chessboard? pennies

This is a geometric progression with a common ratio of 2.

The sum of all the pennies in the first row (8 elements) is 
     

There are 255 pennies in row 1. 

In rows 1-4, there are 32 squares. So the sum is 
     

There are 4,294,967,295 pennies in the first 4 rows.

There are 64 squares in all. So, the sum of all pennies is 
     

There are 18,446,744,073,709,551,615 pennies on the entire chessboard. 

Dis the correct  answer