How is 6:30 PM expressed in military time?

To convert standard time to military time, you add 12 to any hour greater than 12 PM (noon). For the time of 6:30 PM, you start with the hour, which is 6, and since it's in the PM, you add 12 hours to it. This means 6 PM becomes 18 in military time. The minutes remain the same, so 30 minutes past the hour continues to be represented as 30. Therefore, 6:30 PM in military time is expressed as 1830.

This understanding relies on the military time format where the hours are expressed in a 24-hour clock system, starting from 00:00 (midnight) all the way to 23:59 (one minute before midnight).