Engineers and "exact" calculations

Here is an interesting fraction from our good friend Richard Feynman. I use this as an illustration whenever I talk to engineering students about significant digits and uncertainty. 1 / 243 = 0.00411522633744855967…

Nothing in the engineered world can touch the precision of this fraction. And yet, I remember as an undergrad engineering student wanting to be very exact and as a result would compute the design moment or capacity of a beam as something like:

452.83726583243 kip-ft

Nevermind that:

So, all things considered, I think it’s okay to report the beam’s capacity as a cool 450 kip-ft. This is after all why we learned about significant digits in high school chemistry.