If Comcast is upgrading its cable boxes and has $600$ obsolete boxes in ending inventory.

$\backslash$table$[[$Beginning inventory and purchases,Boxes,Box cost,Total cost$],[\{$

$\backslash$table$[[$Beginning inventory: January $1],[$March $1]]\},16,900,|[$$$],[29],[30],[34],[37],[46]|,$$$490,100$