ISO 17:1973

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.