The difference between the _turnover_ and _sales_ is the _gross profit_--being the amount necessary to balance the debit and credit columns. The gross profit is brought down and entered in the credit column. Sales expense is entered in the debit column, the difference between this amount and gross profits being _net trading profit_, for the current month. The three columns at the right are for comparative figures. In the column headed _to date_ is entered the total sales, turnover, gross profits, expense, and net profits from the beginning of the current fiscal year to date; in the two columns next following, the same facts are entered for last month and last year. [Illustration: Fig. 8. A Form for a Monthly Trading Summary] As a rule, these monthly trading statements for each department give the manager just the information he wants; but, when there are a large number of departments, it is sometimes advisable to tabulate these statements, giving one complete record. A form for such a report is shown in Fig. 9. No detailed explanation of this report is necessary, the columns being arranged for the same information as given on the department statement. The only exception is the inventory column, which is intended for the current inventory only. In the three comparative columns at the right, net profits only are entered. This statement gives a history of sales in a nut shell. =Customers' Profit Records.= To know the value of each customer, as measured by the profits on his business, is as important as a knowledge of the value of each salesman. It is for the purpose of obtaining this information that columns for calculating net profits are added to the statistical department's copy of the invoice, Fig. 2. Detailed records of purchases of each customer, divided by commodities, are unnecessary, but there should be a summary showing total purchases and profits. Detailed information about individual shipments and separate commodities can be obtained from the invoice copies. Fig. 10 shows a form for a customer's record on a 4-in. X 6-in. card. This form provides for monthly records only. At the end of the month the total purchases and total profits are obtained from the invoice copies, and the amounts entered on the card. The card is ruled for a two-years' record. These cards should be filed geographically, the name of the town heading the card. If there are several customers in a town, their cards should be arranged in alphabetical order. State boundaries need not be followed; it is usually better to file the cards according to salesmen's territories. This makes a combined customers' and territorial file, and if a record of the business in a town or state is wanted, it can be obtained from the cards. If desired, a new card can be inserted for a total record of each town or group of towns.