Love it!. Searched for a simple math calculator FF extension that would accept keypad entries as well as mouse click, and also save the result for some time . This one does it all very well. A few suggestions/new features..(1) option to copy the result , (perhaps with a dedicated copy button?) (2) is it possible to keep the calculator open across tabs/sites just in case the use wants to keep a running total/calculations using data from various tabs/sites?. Obviously there is a lot of scope for expanding the extension or new ones for - eg, option for date calculations (diff between two dates, no of days/hours to a given date - past or future, etc); or currency convertions/calculations; or interest calculations (discount/tip/mortgage/simple/compound/EMI etc). Thanks a lot anyway