I found the old 2 x 3.14158 x r used to come in handy for profiling on an arc.
Or the square root of 1.5 times the altitude for VHF reception.
But apart from that it's mainly conversions between weights and the old 3 x profile.
The Metro was a good conversion aircraft, pounds to litres, gallons to pounds, litres to kilos - was pretty easy for a new FO to cock up refueling, I did it once in a big way much to the chagrin of my pmsing skipper :P