(09-10-2019, 08:21 AM)Amie Wrote: Perhaps the teach just wanted to demonstrate tolerance spread in components?
That could easily backfire! There is no guarantee that variation between samples from a single batch will cover anything like the maximum possible range. [EDIT: Just spotted that Jeffrey beat me to it while I was writing this!]
A calculator would be simpler!
Or even a chart, such as the one I posted for you in this post.
It was only when I produced that chart that I spotted an anomaly which had completely passed me by many years earlier. Virtually all postwar radio and TV production in the UK, up until the early 60s used large numbers of of Egen ½W resistors. These are quite bulky compared with more modern counterparts because the resistive element was inside an off-white ceramic tube (which showed off the colour codes very well!) with a cement seal on each end.
They were virtually all ±20% tolerance. Now ±20% tolerance only needs 6 values (E6) to cover each decade, yet they were made and sold in the E12 values more suited to ±10% tolerance components!