This extension has numerous accuracy concerns. For example, compare the result of 1/64 on this extension to what your phone says. If you're interested in a better experience, check out my extension: https://addons.mozilla.org/en-US/firefox/addon/address-bar-math/

I haven't added all the constants yet or the saved history but this is otherwise at feature parity and should function better for most use cases. Cheers!

There's probably something I don't see, but I can't find how to actually use this extension. I'm typing simple math in the address bar (ex: "2+2") and I only see google results.
What am I missing?

Nice, but could you add percentage? For example, 120+10%=132.
And how to access history in a new tab without adding a new entry to it?

Excellent one. Don't wait for crappy server connection if you don't have enough bandwidth. Keep up good work.

Simple and powerful, doesn't rely on external servers :)