1 o'clock = 1時 (ichi-ji)
2 o'clock = 2時 (ni-ji)
3 o'clock = 3時 (san-ji)
4 o'clock = 4時 (yo-ji) not yon-ji❌
5 o'clock = 5時 (go-ji)
6 o'clock = 6時 (roku-ji)
7 o'clock = 7時 (shichi-ji) not nana-ji❌
8 o'clock = 8時 (hachi-ji)
9 o'clock = 9時 (ku-ji) not kyuu-ji❌
10 o'clock = 10時 (juu-ji)
11 o'clock = 11時 (juu-ichi-ji)
12 o'clock = 12時 (juu-ni-ji)

for question: "what o'clock?" 何時 (nan-ji)

for indicating A.M. and P.M.:
A.M. = 午前 (gozen)
example: 1 o'clock am = 午前1時 (gozen ichi-ji)
P.M. = 午後 (gogo)
example: 1 o'clock pm = 午後1時 (gogo ichi-ji)

#about_time
========================

minutes
1 min. = 1分（ippun)
2 min. = 2分（nifun)
3 min. = 3分（sanpun)
4 min. = 4分（yonpun)
5 min. = 5分（gofun)
6 min. = 6分（roppun)
7 min. = 7分（nanafun)
8 min. = 8分（happun)
9 min. = 9分（kyūfun)
10 min. = 10分（juppun)
11 min. = 11分（jūippun)
15 min. = 15分（jūgofun)
20 min. = 20分（nijuppun)
25 min. = 25分（nijūgofun)
30 min. = 30分（sanjuppun)
40 min. = 40分（yonjuppun)
50 min. = 50分（gojuppun)
60 min. = 60分（rokujuppun)
#about_time
====================

seconds
1 sec. = 1秒（ichibyō)
2 sec. = 2秒（nibyō)
3 sec. = 3秒（sanbyō)
4 sec. = 4秒（yonbyō)
5 sec. = 5秒（gobyō)
6 sec. = 6秒（rokubyō)
7 sec. = 7秒（nanabyō)
8 sec. = 8秒（hachibyō)
9 sec. = 9秒（kyūbyō)
10 sec. = 10秒（jūbyō)
20 sec. = 20秒（nijūbyō)
30 sec. = 30秒（sanjūbyō)
40 sec. = 40秒（yonjūbyō)
50 sec. = 50秒（gojūbyō)
60 sec. = 60秒（rokujūbyō)
#about_time
===================