Forgive me Smitty I still not sure if you are kidding or are serious. How is wrapping some tape around a tube harder than trying to remember and figure out a formula. I use that method all the time. Especially if i have a piece of material I want to wrap around a tube such as Carbon fiber. I wrap a small bit of tape on both ends of the tube. Slice in half. Pull the tape off and place on the CF. Do both sides. Now take a straight edge and put on edge of both tape ends and slice. No measuring and it has to fit exact. Could not be any easier than that.
If you are trying to figure measurements out to print decals, measure length of tape using a rule or if have to be precise use your calipers. No math involved at all.
That is an old school method that is older than you are

I have seen people do it with string. Look for some tape or look for the calculator. HMMMM toss up.
I just had a funny vision pass through my head. I can see the insulator on the job site out there with a calculator and calipers trying to figure out how much insulation he needs to wrap each pipe that is different diameters. Hold on boss I got this. 2 divided by 4 times pie now is that apple pie or cherry pie.:biggrin::biggrin: Sorry I could not help myself.