Euler problem 06

The sum of the squares of the first ten natural numbers is, 1² + 2² + ... + 10² = 385

The square of the sum of the first ten natural numbers is, (1 + 2 + ... + 10)² = 55² = 3025

Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025  385 = 2640.

Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

Alterate solution:
LINQ is also well suited for solving this kind of problem:

Problem06 =    25164150 elapsed time:    0 ms. Test Passed.