Writing equations in multiple lines

• Writing equations in multiple lines
  • Option1: Use multline
  • Option2: Use split

Illustration

\documentclass{report}
\usepackage{amsmath}
\begin{document}
\begin{multline}
SUM = A + B + C + D + E + F + G + H + I + J + K + L + M\\
+ N + O + P + Q + R + S + T + U + V + W + X + Y + Z
\end{multline}
\begin{equation}
\begin{split}
SUM = A + B + C + D + E + F + G + H + I + J + K + L + M\\
+ N + O + P + Q + R + S + T + U + V + W + X + Y + Z
\end{split}
\end{equation}
\end{document}

Ref: Post by sparkandshine