Addition of odd numbers (edited)

Let $S \subset \mathbb{N}$ be the set of the first $n$ odd numbers greater than zero. If $S_j$ is the $j^{\text{th}}$ element of $S$ , find $\displaystyle \sum_{j\le n} S_j$ for $n = 10^{15000}$ .

Enter the number of zeros in this sum.