Simple Calculator Extension od Wesley-Blake

This is a simple calculator that uses the keyboard for building an expression to evaluate. Once you press enter, the result is displayed and copied to your clipboard. Additionally, if you give it permission to access a site, double clicking on a field will pop up a similar expression field, on pressing enter will replace that field with the result and copies it to your clipboard.

Some additional features are light/dark theme toggle, viewing a list of all sites given permission, revoking permission (as you would expect), adding a previous expression you entered to your current expression by selecting the item from the history field below.