Round the clock
The round the clock function treats your h:m:s or h:m calculations as time of day if you work in the standard 24hour clock. For example, if enter 23:59, the calculator will treat this as 11:59pm. If you now add two minutes, the answer will be 0:01 - one minute past midnight. If round the clock mode is turned off, then the answer would be 24:01. This feature is very useful if you are working out time sheets etc.
Here, 2 minutes have been added to 23:59. As round the clock is turned on, the answer is 0:01. The clock icon in the top right indicates that midnight has been crossed once
Example: you start work at 9pm, finish at 3:30am and now want to calculate the time you have worked. Enter your finish time (03:30) then minus the start time (21:00) and the answer will show you 6 hours 30 mints. Also note that midnight has been crosses once in reverse