Subscript of sum [duplicate]

Question

How can I make a subscript for sum in latex like the following picture:

I tried \sum_{q_i} but that doesn't make the result I want. It makes the following result:

Answer 1

That is expected; it's a matter of inline math mode versus display math mode.

Inline math is meant for small fragments inside the running text, so it is typeset in a compact way, with the subscript to the side of the sum symbol. Inline math is done with $...$.

Display math is meant for larger, standalone equations, and is set in a paragraph of its own. Because it has more space, the subscript can be put underneath the sum symbol. Display math is done with \[...\] or a whole variety of environments.

Answer 2

I tried it out rightnow. If you write something like

  \begin{equation}
  \sum_{q_i} {p x r}
  \end{equation}

It should give you the result you do not want to have, but if you enter mathmode in text

 I want to show you this sum $\sum_{q_i} {p x r}$ blabla

Then you would get theresult you want to have.