\begin{equation}
math formula
\label{eqno1}
\end{equation}
The equation environment centers your equation on the page and places
the equation number in the right margin.
The \label command is required only if you want to use a \ref command to refer to the number assigned to this equation.
The Display Math environment gives the same effect without the equation number. LaTeX will not break lines in displaymath or equation environments (but one may use eqnarray instead).