Calculating Time Duration in Google Spreadsheet

In this video we:
1. set the data type "time" for the specified columns
2. set the data type "duration" for a specified column
3. calculate the duration of an activity by subtracting the starting and ending time of the activity

[manojchauhan]

Thanks. Nice videos. But if date also different, then how we calculate time.
Pls help

[StudioDesignStudio]

This was helpful, is the a way to break it down to days?

[JamestheZinHondo]

Exactly what I was hunting for. Thank you!