The percentage columns shown give us what may be considered a very close figure as to what are the actual factory conditions of operating expense and productive labor, and the relationship of the former to the latter. These results are all the more reliable because they are based on actual figures taken from the books of the company, thereby eliminating all estimating and the basing of important calculations on guesses and assumptions, which later generally prove to be far from the real facts in the case. The above results, gathered from six months' operation of the plant, are a fair statement of what the same expenses will be found to be in the long run, although if it is desired to go into the matter still deeper, the same tabulation may be made covering a year, with practically the same results. What do the above figures show? (a) That the total operating expenses of the plant are 59.1% of its productive labor, of which amount, 32.6%, is necessary to cover the general expenses, and 26.5%, the average for all shop operations. (b) That the expense of operating the different productive departments vary according to conditions. That while _Department E's_ expense is found to be 21.8% of its productive labor, that for _Department F_ is found to be but 17.3%; each department having its own rate based on its own actual figures. (c) Since, as already shown, each department must shoulder its own expense and its share of the general expense, it is seen from results just shown that for every dollar spent on productive work in _Department E_, 21.8 cents must be added to cover its own operating expense, and 32.6 cents as its share of the general plant expense, and that every dollar spent on production here cost $1.544. This has been covered in detail under heading, _True Cost_. =21. How to Use Percentages.= Let us continue the use of the same figures. It is apparent that, if to the cost of each productive order worked on in _Department E_ during the period of six months just considered──all of which is shown in detail in _Production Ledger No. 2_, the sum total of whose labor cost is $104,409.00──21.8% is added, the amount thus added will be $22,731.00 (the actual figure is a trifle more), which is just the amount of _Department E_'s expense shown in the _Private Ledger_ and found in detail in _Expense Ledger No. 1_. Again, if to the cost of each productive order worked on by any and all departments in the plant during this same period──the sum total of whose labor cost is found to be $208,133.21 and which is shown in detail by the individual cost sheets in _Production Ledger No. 2_──32.6% is added, the amount thus added will be $67,840.00 (actual figure is a few dollars more), which is just the amount of total expense shown by the _Distribution Account_ in the _Private Ledger_.