A square decameter (often abbreviated as dam²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 10 meters (1,000 centimeters) in length.
One square decameter is equal to 100 square meters (m²) because each side of the square is 10 meters long, and when you square that length, you get 100 square meters.
Square decameters are not as commonly used as some other units of area, but they can be used to describe moderate-sized land areas, and they are a part of the metric system for measuring area.
A square yard (sq yd or yd²) is a unit of area commonly used in the United States and a few other countries. It is defined as the area of a square with sides that each measure one yard (3 feet) in length.
In terms of square feet, one square yard is equal to 9 square feet (1 yard * 1 yard = 3 feet * 3 feet = 9 square feet).
In terms of square meters, one square yard is approximately equal to 0.836127 square meters.
Square yards are often used in various applications, including real estate, landscaping, and construction, especially in the United States where the customary system of measurements is still prevalent.