The square of the sum of the first ten natural numbers is,

(1 + 2 + ... + 10)**2 = 55**2 = 3025

The sum of the squares of the first ten natural numbers is,

1**2 + 2**2 + ... + 10**2 = 385

Hence the difference between the square of the sum of the first ten natural numbers and the sum of the squares is 2640:

3025 - 385 = 2640