Clock and calculator Qs

I'm on 2.7.15 How in the world do you make the desktop clock read bios clock and keep correct time? i'm a linux newb
Did this version really ship with NO calculator???

Are you talking clock drift, always resetting to (eg) 00:00, a timezone offset, or something else? If it's drift, that's normal... clocks drift, some are shockingly bad. A lot of times you don't see it because OS's are configured to sync to the Internet regularly. You can check the time in the BIOS to verify that. If you don't have an internet connection on the machine, you're probably stuck with the drift/manually adjusting it occasionally.

Always resetting to 00:00 is probably a dead battery, timezone offset is likely misconfiguration or (if you're dual-booting) Windows and Linux fighting over whether BIOS time is localtime or UTC.

No calculator... pretty sure it has Python installed, which IMO is the best calculator around.

sudo apt install galculator

cayenne@LinuxCNC:~$ sudo apt install galculator
[sudo] password for cayenne:
sudo: apt: command not found

This worked
sudo apt-get install galculator
But returned nothing but a bunch of 404s

I'm on ver 2.7.15 and everything I try and install including with the synapptic thing it all returns 404s

sudo apt-get update
before
sudo apt-get install xxxxxxxxx