50×50=2500 (square centimeter) =25 (square decimeter)

60×60=3600 (square centimeter) =36 (square decimeter)

The least common multiple of 25 and 36 is 900, and the unit here is square decimeter. If you ask about square meters, you need to change units.

900 square decimeter =9 square meters

A: The ground is at least 9 square meters.