From 1 to 10, numbers should be written out: one, two, three, etc...
Above 10, numbers should be written numerically: 11, 12, 13, etc...
If there are too many numbers in a line, write numbers numerically
Use numerals when exact times are emphasized: 9:30 a.m.
Use lowercase a.m. (ante meridiem) and p.m. (post meridiem)
Use numerals when exact times are emphasized with a.m. (ante meridiem) and p.m. (post meridiem): 6 a.m., 8:30 p.m.
If the more general 'o'clock' is used, however, all numbers should be written out: four o'clock, eleven o'clock
Spell out words/phrases that do not include actual numbers: half past, quarter to, midnight, noon
Dates should be written as numbers instead eg. 1987
Decades should be written like this: '60s