Both names are from Latin, and numbered from 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. Time from midnight to noon is a.m. and from noon to midnight p.m. The table at right shows how it relates to the 24-hour clock. Most places in the world use a 12-hour clock for their normal working lives. In Canada and the US the military uses the 24-hour system.