Where can I get a hexadecimal or binary calculator that will help me manage hex and binary numbers?
Do you mean like this?
That's just the standard Calculator App on Mac OS X after hitting Command+3. The standard Windows 7/8 calculator has a very similar switching capability.
On Linux, most people recommand qalculate.
There is a whole pile of choices on Android - just Google!
There are also many listed in the IOS App store, but Pcalc seems to be the clear leader. You can add a $2.99
Programmer Pack to the free Lite Version or get the full version (which includes that and more) for $9.99.