Answer
10,100
Work Step by Step
Find the first few sums and look for a pattern
1 term, 2=2
2 terms 6=2+4
3 terms 12=9+3
4 terms 20=16+4
Each sum is the product of the number of the terms and the number of terms plus 1. The value of the $n^{th}$ term is $n(n+1)$, so the 100th term will be $100\times101=10100$.
