For users of Mozilla Firefox, you have an inbuilt Google Search box on the top right corner of your browser. This Google Search box, based on Google suggest feature, can be used as your personal online calculator.
Online Calculator using Firefox
To use Google’s built-in calculator function, simply enter the calculation you’d like done into the search box and hit the Enter key or click on the Google Search button. The calculator can solve math problems involving basic arithmetic, more complicated math, units of measure and conversions, and physical constants.
Now, with the Online Calculator using Firefox, you don’t have to press Enter or anything else to get the Google Calculator results.
You can learn more about the various other operators for Google Calculator here