I have learned...memorized... and relearned & re-memorized that 5/9th formula for 60 years. I'm glad they just DO it these days. Besides, I doubt that many folks anymore CAN multiply by 5/9ths and 9/5ths in a reasonable amount of time.

I see the advantages of both systems, and it may be that I just grew up doing F, but it 'seems' easier having more whole #s rather than sticking .5s to be accurate.

No matter, I have my programs to convert furlongs to fortnights ...and C to F anytime it's relevant.