As Justin Pot writes in How To Use Google As A Calculator, the Google Search Calculator associated with the Google search engine is particularly helpful because that search page is often already up on most peoples' web browsers. This makes it easy to perform different calculations without having to bring up different, separate tools.
I include several screen snapshots in this post to illustrate different mathematical computations that can be performed using the calculator built into the Google search engine. The first examples show basic arithmetic (addition, subtraction, multiplication, division) and use of parentheses.
The calculator built into the Google search engine can do more than basic arithmetic. The next examples demonstrate use of exponents.
The next screen snapshots demonstrate Google search calculator's support of the keyword "Pi", square root functionality, and imaginary numbers.
The Google search calculator also supports trigonometric functions such as sine, cosine, tangent, and the inverse/arc versions of each of these. Radians are assumed unless degrees are explicitly specified. The following screen snapshots demonstrate these concepts.
The Google search engine's built-in calculation capabilities go beyond the simple mathematics shown above. The post Google Is Now a Graphing Calculator discusses this more and provides an example that can be pasted into the Google search engine.