Hear, hear. I keep being amazed how little sanity check is done when it comes to numbers. I developed a rule of thumb over the years: if you can't Fermi estima

Hear, hear. I keep being amazed how little sanity check is done when it comes to numbers. I developed a rule of thumb over the years: if you can't Fermi estimate some metric or quantity within an order of magnitude, you probably don't understand the metric very well. If you can't estimate it within two order of magnitudes, you probably don't understand it at all.