Elapsed time is determined by subtracting the start time from the end time of an event.

To calculate the elapsed time, you must know both the start time and the end time. The fundamental formula for this calculation is:

You can express the times in hours and minutes, and sometimes in seconds, depending on the desired level of precision.

For example, if an event starts at 2:30 PM and concludes at 4:45 PM, you may want to convert these times into 24-hour format. In this case, 2:30 PM is represented as $14:30$, and 4:45 PM as $16:45$. You then perform the subtraction:

To carry out this subtraction, you can separate the hours and minutes. First, subtract the hours:

Next, subtract the minutes:

Thus, the elapsed time is $2$ hours and $15$ minutes.

If the minutes of the end time are less than those of the start time, you need to borrow $1$ hour (equivalent to $60$ minutes) from the hours portion. For instance, consider a scenario where the start time is $3:50 \text{ PM}$ ($15:50$) and the end time is $5:20 \text{ PM}$ ($17:20$). You would first subtract the hours:

Next, since $20$ minutes is less than $50$ minutes, you will borrow $1$ hour, converting it to $60$ minutes and adding it to the $20$ minutes, resulting in $80$ minutes. Now, perform the subtraction for the minutes:

Consequently, the elapsed time is $1$ hour and $30$ minutes (due to borrowing an hour).

Understanding how to calculate elapsed time is crucial for addressing various real-life situations, such as determining the duration of a journey or the length of a meeting.