When I’m sitting at my Mac and need to do a quick bit of calculation, I typically launch the Calculator app with my app launcher of choice, Alfred.
If you don’t want to launch the app, click on the numbers, or enter in the calculations via that graphical interface, you can just use Spotlight.
First off, activate Spotlight by hitting the Command and Space keys on your keyboard, or by clicking on the little magnifying glass in the upper right of your Mac’s screen.
Now, just type in any mathematical expression. For example, if you type in 44+3-22*(22+1), Spotlight will evaluate the expression super quick with the correct order of operations, giving an answer of -459 in less than a second. Or you can do a quick division problem (44 divided by 3), as in the image at the top of this post. The complexity is up to you.
You can do any mathematical expressions with the / (division), + (add), – (subtract), and * (multiply) keys on your keyboard. You can even do fun things like cosine (cos) or sine (sin) for your more advanced mathematical functions.
Now you have a quick and easy way to do your math calculations without even having to launch a calculator on your Mac. Cool stuff, right?
Via: Stack Exchange