Sorry for the delay in receiving a response! You can change the number of decimal points showing by right clicking on the measure in the data window and selecting Default Properties>Number Format...>Number (Custom) and type in the desired number of decimal places.
Hope this helps!
Thank you Tracy! This was very helpful!
I understand your question. Very interesting question, and I'm surprised I haven't thought about it before.
The maximum number of decimals that one can display in Tableau is 16. However, PI only displays to the 14th decimal, so I'm going to say to the 14th decimal.
PI()/2 returns 1.5707963267949000
The 3 ending zeros tells me that while Tableau can display >14 digits, in calculations, it is only factoring up to the 14th digit.