You can use the following abbreviations with numerals. Notice that ad precedes the numeral; all other abbreviations follow the numeral. Today, bce and ce are generally preferred over bc and ad, and periods in all four of these abbreviations are optional.
| 399 bce (“before the common era”) or 399 bc (“before Christ”) |
| 49 ce (“common era”) or ad 49 (anno Domini, Latin for “year of our Lord”) |
| 11:15 am (or a.m.) |
| 9:00 pm (or p.m.) |
For these abbreviations, you may use full-size capital letters or small caps, a typographical option in word-processing programs.