12 hour clock

It was a bright cold day in April, and the clocks were striking thirteen.
—Orwell, 1984

24-hour clock	12-hour clock
0	12 a.m.
1	1 a.m.
2	2 a.m.
3	3 a.m.
4	4 a.m.
5	5 a.m.
6	6 a.m.
7	7 a.m.
8	8 a.m.
9	9 a.m.
10	10 a.m.
11	11 a.m.
12	12 p.m.
13	1 p.m.
14	2 p.m.
15	3 p.m.
16	4 p.m.
17	5 p.m.
18	6 p.m.
19	7 p.m.
20	8 p.m.
21	9 p.m.
22	10 p.m.
23	11 p.m.