If you have ever experienced writing down the same formula multiple times in the same text field in TurboTax, you would have found the process to be rather annoying. That is where HotCalc comes in.

This extension for Chrome solves a very specific problem: if you type in a mathematical expression and hit the tab button or click out of the field, the solution will replace the content of the text field. 

This can be very useful in quickly solving certain formulas you need to type into a text field in order to calculate.