\nonstopmode
\documentclass[12pt]{article}
\pagestyle{empty}
\begin{document}
$$
U=P_{{F}}+{\frac  {N\cdot A_{{t}}\cdot (1-P_{{F}})}{(N+\lceil {\frac  {T_{{o}}}{A_{{t}}}}\rceil )\cdot A_{{t}}}}
$$
\end{document}
