best way to say the 24 hour time [duplicate]

It's rare for people to say "sixteen o'clock". Many people would be more likely to convert the time to 12-hour clock and say "four PM" out loud.

It's common to read out 24-hour times that end in 00 as "hundred".

• 16:00 - "sixteen hundred"
• 16:45 - "sixteen forty-five"
• 16:05 - "sixteen oh-five"

Sometimes, you hear something like "sixteen hundred hours". This is sometimes described as "military time". It sounds illogical, but it is commonly understood.

In the UK, 0400 is o four hundred hours. 1600 is sixteen hundred hours. No one says sixteen o'clock. Otherwise, much as Slim says.