sentence: This cannot be done with 11. No matter how the rectangle is arranged, there will always be blocks left over, except for the rectangle with sides of lengths 11 and 1. 11 must therefore be a prime number.
modified: This cannot be done with 11 No matter how the rectangle is arranged there will always be blocks left over except for the rectangle with sides of lengths 11 and 1 11 must therefore be a prime numbest