There are two ways to express the duration of 100 minutes:

1. **Hours and minutes:** 100 minutes is equal to 1 hour and 40 minutes. This is the most common way to express time for durations that don't span a whole number of hours.

2. **Decimal hours:** 100 minutes can also be expressed as 1.667 hours. This format is useful for some specific applications, like calculating rates or durations that involve fractions of hours.