A square chain is a unit of area measurement that is now considered obsolete and not commonly used. It was historically used in some English-speaking countries, including the United States and the United Kingdom, as part of the older system of land measurement.
One square chain is equal to an area of 10 square rods, or 484 square yards. In terms of square meters, one square chain is approximately equal to 404.68564224 square meters (m²).
The square chain was often used in land surveys and property descriptions in the past, but it has been largely replaced by the more standardized metric and imperial systems of measurement. In modern times, square meters and square feet are the more commonly used units for measuring land area.
A square decimeter (often abbreviated as dm²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 1 decimeter (10 centimeters) in length.
One square decimeter is equal to 0.01 square meters (m²) because each side of the square is 10 centimeters long, and when you square that length, you get 0.01 square meters.
To put it in perspective, a square decimeter is a relatively small unit of area. It is often used for measuring small areas, such as the surface area of small objects, pieces of paper, or the dimensions of certain materials in scientific and technical contexts.