What 24-hour format time is indicated by 1800hrs?

In the 24-hour time format, the hours are counted from midnight (00:00) to just before the next midnight (23:59). Therefore, to convert a 24-hour time format to the 12-hour format, you can follow a simple rule.

When the hour is 18 (as in 1800 hours), you subtract 12 to convert it to the 12-hour format. Doing this gives you 6:00. The designation of "hrs" indicates it is PM because the 24-hour clock counts from 00:00 to 23:59, with times from 00:00 to 11:59 being AM and from 12:00 to 23:59 being PM.

Therefore, 1800 hours signifies 6:00 in the evening, or 6:00 PM. This makes the first option the correct answer.