Answer:
1245 a.m. is 0045 and 12:45 p.m. is 1245
Explanation:
Midnight starts with 0000 and each hour until 1 p.m. starts with the actual hour number; 1 p.m. starts with 1300 and each hour thereafter adds another 100 (2 p.m. is 1400 etc.) with it ending at 2359 one minute before midnight.