I am very new to Mathematica. I am trying to do some manipulations using mathematica, I am solving functions using FullSimplify function of Mathematica. It gives me unpleasant approximations of Pi Whereas in my friends laptop It gives exact things like . How can set my mathematics to not to approximate Pi/2 as 1.5708 and give numbers O(1.e-16) as zero. Simply How can I configure my mathematica to get same behaviour.