U may or may not be knowing google has a Google's built-in calculator function

It takes expressions like
2*7+6
4^6
4th power of 64
Square root of -81
56 in roman
7! (i.e. factorial)

Also universal constants like
G Gravitational Constant
c Speed of light
e logarithmic base
pi Circumference/diameter
phi the golden ratio( or divine ratio as per da Vinci code)
etc. also supported…..

You wont like to use windows calculator if u do a little bit of
tweaking with it....
Do say thanks to me if u feel I have increased your knowledge…
feel free to add your comments....