Lebsack Ltd uses the perpetual inventory system. The following table shows beginning inventory and inventory purchases for $2017$ :

$\backslash$table$[[$Month$,$Sales Units,Purchases$],[$Units$,\backslash$table$[[$Cost per$],[$unit$]],$Totals$],[$Beginning Inventory,,$840,$$$4\mathrm{.}00,$$$3,360$