Asklemmy

I can't say "professionally" but I learned CAD design with FreeCAD, and know the topological naming issue thoroughly.

Almost all "mystery" problems in CAD are due to a combination of the hacks that get around the Topological Naming Issue and π.

In CAD, you cookie, you brownie, you might even salad, but you stay the hell away from importing π as a reference on anything complex. For 3D printing, I never need better than 0.05mm so 3.1416.

Embedded engineer, working in education. I use 3 for mental estimations and whatever is stored in the calculator, I have happened to grab, for "precision" work. Sometimes I'll even round pi to 4, to build in some tolerance when calculating materials.

Mechanical engineer here - Matlab uses 16 digits for pi(), so that's my go-to. When doing some larger thermodynamic simulations, I sacrifice some digits of pi to get more computational headroom. But that's only after I get really annoyed at the code, and it almost never helps (but rarely hurts, as well)

Well, I have two answers. If it is mental math I use 3.1 and round up. If I am calculating something I care about I use my TI-86 which has pi to 14 digits.

Practically speaking, I don't often need to convert diameter to circumference but I do occasionally need to calculate area or volume and in those cases I have way more error in other measurements or assumptions (2 or 3 digits) so 5 digits of pi is more than enough.

Back in middle school I memorized this much of pi (for no good reason):

3.14159265358979323846264338327950288419716939937510

That’s far more accurate than I’ll ever need.

I'm a programmer and I remember 33 digits, but in practice I never use pi because I never have to deal with geometry

I'm a nothing in particular, and I used to remember 100 digits. I could probably remember again in an hour.

I'm British, not American, so I use 7/22.

I use 100,000,000,000,000

I use 100 trillion digits

I use 100 trillion digits

Prototyping. I just checked and my slide rule has a notch for pi. So, all of them.

I'm an auditor. Zero digits is the norm if I have to use Pi there is something VERY wrong

baker. I measure pie based on how much I can fit in my mouth

Mechatronics student. If your not using 3.1416 at a minimum, then your doing it wrong.

Mostly I'll just go with M_PI.

355/113 = 3.14159292035398 is close enough for my needs.

I don't use Pi but I do use GPS fairly often and try to get down to 7 digits after the decimal point. Our equipment probably isn't quite that accurate though lol so the seventh digit is likely a guess. Probably even the 6th digit.

As a pilot I can't think of a time I've ever done numbers math with pi. Private pilots are taught to use an E6B flight computer, which is basically a device for accurately drawing and measuring the triangle you're looking to solve instead of doing algebra and arithmetic.

In the wood shop, if I do have to do algebra rather than just drawing a circle with a compass, I'll use 3.14, and I still have to round to the nearest 32nd of an inch.

I am a farmer who has to graft pipe cuts at various angles. i use 3.14159. which is plenty since i am measuring my cuts to the nearest eighth of an inch and i am not sending this ish to the moon.