I want to be able to replicate this excel file I saw on a different post. What excel functions are at play here? Thank you!

\begin{tabular}{|r|r|r|r|} \hline Quarter & \multicolumn{1}{|l|}{ Demand } & Regular Production =Demand & Ending inventory \\ \hline Previous Quarter & 1500 & & 200 \\ \hline 1 & 1900 & 1900 & 200 \\ \hline 2 & 1400 & 1400 & 200 \\ \hline 3 & 1500 & 1500 & 200 \\ \hline 4 & 1900 & 1900 & 200 \\ \hline 54m & 5500 & 5500 & 800 \\ \hline \end{tabular}