Use Google as a Calculator

You can enter simple maths into the Google search box (Link) and it will give you the answer.

For example:
4*5
3+2
5^3

and it can even translate into different types of measurement:
4lbs in ounces
4km in miles

If you type in "the answer to life, the universe, and everything" into Google, the calculator gives you the answer... 42.