Hey, I've got 2 unsolved problems that need help!
1. Find the sum of the multiples of 7 which are less than 10000.
My answer is 714264285 but the book says 7142142?
2. Find the sum of the series n + 2(n-1) + 3(n-2) +...+ n.
A step by step guide would be really appreciated for this one.
Thanks in advance!