Sample test question, get the how, sort of, don't understand the "why?

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Looking at the government website regarding apprenticeships and drilling down a few layers to the Red Seal information, they had 20 something sample questions, I did OK missing the ones about submerged arc as that is way way out of my realm.The test question that I wonder about not understanding the "ins and outs" was as follows:What angle of cut is required to make a template for a three piece 90* elbow?
Reply:The unicode degree sign is this, not like it matters too much: °i think they're basing it off two 45° angles, instead of three 30° ones. I'm not sure what advantage that would confer, though. Maybe there's less friction or turbulence inside the tube using a less sharp angle, kind of like in the old story where the Aztec wind god kept banging himself on the corners of his temple?
Reply:Russ, I'm not a pipe fitter but I can visualize what they are wanting. Lets say you have 3 pcs. of pipe that you are going to make your 3 pc. 90 out of laid on your table end to end. Left end of left pipe is straight 90 cut. Right end of left pipe cuts 22.5 Left end of center pipe cuts 22.5 Now you have 45 degrees of the 90 you need. Right end of center pipe cuts 22.5 Now you have 67.5 of the 90 you need. Left end of right pipe cuts 22.5 and right end of right pipe is square 90. Now you have 90 degrees of bend in 4 cuts ready to weld up, and both ends of your welded 90 square cut ready to weld to your mainline. That's how I see it anyway, and it wouldn't be the first time I was wrong.    ChuckTo ride, shoot straight, and speak the truth. This was the ancient law of youth. Old times are past, old days are done, but the law runs true oh little son.Winpower 180 DCSA-200 redfaceXMT-304
Reply:On an elbow regardles of the angle or degrees take the number of pieces, subtract 1 then double that number. Then divide that number into the # of degrees. For example a 5 piece elbow 90 degress would be 8 into 90 degrees for approximately a 11 degree cut. On a small diameter 11 degrees would be close enough, but on a large diameter 11.25 degrees would be better.
Reply:The angle of each cut has to match.  One end - 22.5middle - a cut on each end at 22.5Other end - 22.5Four cuts at 22.5 = 90."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Thanks all.Oldenum: sometimes its just the way the explanation is, and yours "tweaked" my mind.  I was not counting the originating pieces as a piece, I was connecting the two end pieces with 3 pieces in-between, trying to relate it to threaded pipe fittings.M J D: like the math "trick" easy to remember and apply