How can print this type of summation?

Question

I am a new latex users and in a report must print this type of summation

What is the latex code

Thanks to Steven B. Segletes I have obtained this result:

I need to reduce the space highlighted

Answer 1

\documentclass{article}
\usepackage{amsmath,amssymb}
\begin{document}
\[
\sum_{\substack{0\le x<100\\x\in\mathbb{Z}}} f(x)
\]
\end{document}

To keep the substack from affecting the function offset, one can use \mathclap from the mathtools package:

\documentclass{article}
\usepackage{amsmath,amssymb,mathtools}
\begin{document}
\[
\sum_{\mathclap{\substack{0\le x<100\\x\in\mathbb{Z}}}} f(x)
\]
\end{document}