When it comes to calculations, the most useful ability is not to be able to

caculate it exactly, caculator or no, but to quickly be able to estimate a ball

park answer or approximation.

Who needs to know that  22uH at 137kHz has 18.93 ohms reactance.

Its quicker to think  " a bit more than 20 times a bit less than 0.14, times
6-and-a-bit
...    is  2.8 times 6-and-a-bit ,  so call it 18 ohms"

And they don't teach that in schools - and never have done, to my knowledge!

Mike
--
M.J.Powell