When u are doing math and u have a question with pi in it don't u use "3.14" or do u use "3.141" or is it "3.14159?

It ultimatley depends on your teacher, or the question you are answering. Some questions will specify, saying something like "Use 3.141 for pi", or sometimes teachers will always want you to use a specific number for pi. Personally, I use as many places of pi that will fit on my calculator, and then whatever I get for my answer I will shrink it so that it only has 3 decimal places. Honestly, you should be fine if you just 3.14 for most equations though!

Usually, I use 3.14.