Turning off approximations for Pi

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 enter image description here Whereas in my friends laptop It gives exact things like enter image description here. 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.