> then he would resort to a parallel combination from the fraction Easier to find series combinations and then maybe clean them up with one parallel resistor.

> then he would resort to a parallel combination from the fraction Easier to find series combinations and then maybe clean them up with one parallel resistor. e.g. 4.7 + 2.2 ohms = 6.9 ohms; if you want better, 3.9+3.9 =7.8, and a 68 ohm resistor in parallel yields 6.997 ohms, an error of .04%. Often that parallel resistor will be a trimpot or other adjustable means.