AUC: Arbitrary Unit Calculator
AUC is a calculator that lets you work with whatever units you need, unlike other unit-aware calculators which only work with metric/imperial units or derivatives thereof.
For example, suppose you run a data center with 10,000 hard drives. The manufacture guarantees an average one million hours to a drive failure. Since you have 10,000 drives, however, these hours are accrued in parallel. The million hours are drive-hours, akin to man-hours. Once this is established, figuring out how often to expect failures becomes a simple dimensional analysis problem. However, common software for doing such calculations wouldn't support such esoteric units as drive-hours. This is where AUC comes it - it supports any unit you can imagine.
For example, to solve the above problem, you would write
> (1 failure / 1e6 hdd hr) * 10000 hdd
and receive the solution
1 failure / 100 hr