The discount columns are memorandum columns only, the net cash being entered in the amount columns under purchase and sales ledger. These columns are included that the total payment may be posted to personal accounts in purchase or sales ledger. The totals of these columns are to be posted to discount and interest columns at the end of the month. The total amount to be posted to the debit of the purchase ledger account and to the credit of sales ledger account is made up of the totals of the discount and amount columns. The sundries columns are provided for all entries for which there are no special columns and are used principally for transactions affecting general ledger accounts. These columns are sometimes used for ordinary journal entries not involving an exchange of cash, but their use for this purpose is strongly advised against. The cash book should be used exclusively for recording cash transactions. When columnar purchase, sales, and cash books are used, the journal is only needed for adjusting and closing entries, and for this purpose it is best to provide an ordinary two-column journal. SUBDIVISION OF EXPENSE ACCOUNT =12.= In every business there are several classes of expense and it is very useful to know the exact amount of each class. When all expenses are charged under one head, it is impossible to determine without considerable checking, whether or not any particular class of expense is more than it should be. It is customary, therefore, to subdivide expense and to open accounts in the ledger for different classes of expense. Some subdivisions in common use are rent (paid), insurance, taxes, interest and discount, in freight, out freight, salaries, labor, fuel, office supplies, telegraph and telephone, postage, general expense, etc. The exact subdivisions used must of necessity be governed by the nature of the business. For instance, the item of telegraph and telephone charges may be of importance in one business, while in another, the number of such charges would be so small that a separate account is not warranted. PETTY CASH VOUCHER