Periodic Inventory by Three Methods Dymac Appliances uses the periodic inventory system. Details regarding the inventory of appliances at January 1, purchases invoices during the next 12 months, and the inventory count at December 31 are summarized as follows: Purchases Invoices Inventory, Inventory Count, Model A10 815 E60 G83 134 M90 270 January 1 1st 2nd Grd December 31 8 at 3 at 7 at 12 at 2 at 5 at 4 at 64 4 at 70 4 at 76 176 4 at 158 3 at 170 6 at 184 75 3 at 65 15 at 68970 242 6 at250 5 260 10 at 259 240 10 at 246 16 at 27 16 at 270 108 2 at 110 3at 128 t 130 160 4 at 170 4at 175 7 at 180 15