21.00 twenty-one (hundred) hours

[sitifan]

The time of day
8.00 a.m. eight a.m. /eight o’clock in the morning
10.00 p.m. ten p.m. /ten o'clock in the evening.
7.30 half past seven/seven thirty
half seven (informal)
7.15 (a) quarter past seven/seven fifteen
7.45 (a) quarter to eight/seven forty five
9.20 twenty (minutes) past nine/nine twenty
9.55 five (minutes) to ten/ten fifty five
10.23 twenty-three minutes past ten/ten twenty-three
10.46 fourteen minutes to eleven/ten forty-six
16.08 sixteen oh eight
21.00 twenty-one (hundred) hours

(A Basic English Grammar, by John Eastwood and Ronald Mackin, page 143)

Does the quotation in red mean that 21.00 can read either "twenty-one hours" or "twenty-one hundred hours"?

[Tarheel]

Twenty-one hundred or twenty-one hundred hours

Google "military time".

[emsr2d2]

21.00 twenty-one (hundred) hours

(A Basic English Grammar, by John Eastwood and Ronald Mackin, page 143)

Does the quotation in red mean that 21.00 can read either "twenty-one hours" or "twenty-one hundred hours"?

It certainly appears to be what they're suggesting but I disagree with them. If it's exactly 9pm, then it's only worded "twenty-one hundred hours", and only when using "military time". From 9.01pm onwards, the hundred would be omitted. 2105 = twenty-one oh five.

[PeterCW]

I agree, BrE usage would be "twenty-one hundred" or more likely to read it aloud as "nine PM".

"Military time" is an American expression which would cause most British people to be puzzled. Twenty-four hour times are universal in transportation schedules in Europe and most of us will happily switch between systems in mid conversation.

[emsr2d2]

"Military time" is an American expression which would cause most British people to be puzzled.

I think quite a lot of BrE speakers would understand it but it's certainly more common to the use the term "the 24-hour clock".

Bob: How would you express 9pm using the twenty-four hour clock?
Jane: Twenty-one hundred [hours].

[SoothingDave]

I don't think anyone is saying "fourteen minutes to eleven" for 10:46. Five till, ten till, quarter till all are natural. Not numbers not divisible by 5.

[Skrej]

I agree with Dave. I obviously can't speak for everyone, but I tend to round to the nearest unit of 5 for that very reason, unless there's a need to be precise. If so, then I'll just use the straight number format, and not mess with the to/past format.

For example, at 10:46, I'll just say "(about) a quarter to 11". If I need to be exact, then "10:46" For something like 10:08, then it's either "10 past ten" or "10:08".

I'm writing this post at a quarter past 5 local time. (But it's really 5:17 by the clock on my wall.)

[Tdol]

21.00 twenty-one (hundred) hours

Does the quotation in red mean that 21.00 can read either "twenty-one hours" or "twenty-one hundred hours"?

It does, but I would say it should be twenty-one hundred (hours).

[Rover_KE]

21.00 twenty-one (hundred) hours

Does the quotation in red mean that 21.00 can be read either "twenty-one hours" or "twenty-one hundred hours"?

I haven't read every word of this thread closely, but I don't think anybody says 'twenty-one hours'.