he resistances of commercially-available discrete resistors are restricted to particular sets. For example, the available values of resistors with 10% tolerance are selections from the E12 set multiplied by a power of ten from 100 through 105. The E12 set is:

E12={10,12,15,18,22,27,33,39,47,56,68,82}
Thus, you can buy 10% resistors with a nominal resistance of 330Ω or 33kΩ, but not 350Ω. Furthermore, the "tolerance" means that if you buy a 10% 390Ω resistor you can be sure that its resistance is between 351Ω and 429Ω.

Question

he resistances of commercially-available discrete resistors are restricted to particular sets. For example, the available values of resistors with 10% tolerance are selections from the E12 set multiplied by a power of ten from 100 through 105. The E12 set is:

E12={10,12,15,18,22,27,33,39,47,56,68,82}
Thus, you can buy 10% resistors with a nominal resistance of 330Ω or 33kΩ, but not 350Ω. Furthermore, the "tolerance" means that if you buy a 10% 390Ω resistor you can be sure that its resistance is between 351Ω and 429Ω.

kenljw · Answer

There's equation's to represent set resistance for 5%,10%,20% which are two digits,  There's also for 1%,2% with three digits. also .05%,.1%,.5%, The easiest way is to get an electronic catalog, some manufacturers don't use sets but have there own sequence that are more useful, especially with 1% and .1%