If you’ve been around electronics for a while, you’ve probably noticed that components like resistors, capacitors, zener diodes, and inductors come in some odd values. Looking at the chart below, there seems to be no clear rationale behind the values, but there is a pattern. 47kΩ resistors and 22μF capacitors are everywhere, but not 40kΩ or 50kΩ resistors, or 20μF or 30μF capacitors. So what’s the deal? It all has to do with preferred numbers. We have to go back a few years to 1877 France. The F...