1. Understand the Units:

* Light-year: The distance light travels in one year.

* Kilometer: A unit of distance in the metric system.

2. Conversion Factors:

* Speed of Light: Approximately 299,792,458 meters per second (m/s)

* Seconds in a Year: Approximately 31,536,000 seconds (365.25 days x 24 hours/day x 60 minutes/hour x 60 seconds/minute)

3. Calculation:

* Distance in meters: 4.22 light-years * (299,792,458 m/s) * (31,536,000 s/year) = 3.985 x 10^16 meters

* Distance in kilometers: (3.985 x 10^16 meters) / 1000 meters/km = 3.985 x 10^13 kilometers

Therefore, 4.22 light-years is approximately 39.85 trillion kilometers.