Guide to the use of preferred numbers and of series of preferred numbers

The best scale will be determined by taking into consideration, in particular, the two following contradictory tendencies: a scale with too wide steps involves a waste of materials and an increase in the cost of manufacture, whereas a too closely spaced scale leads to an increase in the cost of tooling and also in the value of stock inventories. In selecting a scale of numerical values, choose that series having the highest ratio consistent with the desiderata to be satisfied, in the order : R 5, R 10, etc.