A square nanometer (often abbreviated as nm²) is a unit of area in the International System of Units (SI) and is used to describe extremely small areas, especially in the context of nanotechnology and scientific research.
One square nanometer is equal to one billionth of a square meter (1 x 10^-9 m²). In other words, it takes one billion square nanometers to make up one square meter.
To give you a sense of scale, a square nanometer is incredibly tiny. It's often used to describe the size of individual atoms, molecules, or the features on nanoscale devices. Nanotechnology deals with structures and materials on this extremely small scale, where traditional units of area, like square meters or even square millimeters, are impractical.
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.