How do I calculate purchases?

Question

In my auditing course we are learning about analytical procedures, but I am having a momentary brain lapse. I have Sales, Cost of Goods Sold, A/P, A/R, and inventory for the current year and the previous year -- how do I calculate purchases (I need purchases to determine A/P turnover rate)?

Answer 1

The formula for COGS is:
Beginning inventory + Purchases - Ending inventory = COGS. You have everything except purchases. Just use a calculator. You're sure to get it.

Answer 2

Here's how:

Purchases = Cost of Goods Sold + Inventory for the current year - Inventory of the previous year