During your audit of the financial statements of The Gary Manufacturing Company for the year ended December 31, 1999, you find that at January 1, 1999, the company had installed the following procedures for recording raw material purchases and payables:

a. Vendors' invoices are sent directly to the accounts payable department by the mail department.

b. All documents supporting the invoices are accumulated in the accounts payable department and attached to the invoices. After being checked and cash discounts computed, the invoices are entered on computers at workstations.

c. An invoice register is prepared from data compiled on-screen.

d. The general ledger control account is posted monthly from the totals shown in the invoice register and all other journals.

e. On due dates, the accounts payable are processed to prepare checks and remittance statements.

f. At the end of the month, unpaid accounts payable are compared with the general ledger control account.

Required: 

List the procedures you would use to audit raw material purchases.