Re: OT: Converting miles/km

On 20/09/24 19:30, Helmut Richter wrote:
 

I like much more those thumb rules that actually allow you to estimate
orders of magnitude, e.g.:
>
1 year ? π · 10? sec ? 31415926.54 sec
>
or
>
1 year ? √10 · 10? sec ? 31622776.60 sec
>
or, only for those wanting more precision, the arithmetic mean of the two
which has three leading digits correct.

 
The one non-metric measurement that I find useful is "one foot per
nanosecond".