Picometer
A picometer (pm) is an extremely small unit of length in the metric system, equal to one-trillionth of a meter (1 pm = 10⁻¹² meters). Picometers are used to measure things on the atomic and subatomic scale, such as the size of atoms or the distance between particles in a molecule. For example, a hydrogen atom is about 50 picometers in radius. This unit is mainly used in physics, chemistry, and nanotechnology. Because it's so small, you won’t see picometers used in everyday life — they are only relevant in scientific research where ultra-precise measurements are required.
Russian Archin
The archin (also spelled arshin) is a traditional Russian unit of length that was widely used before the adoption of the metric system. It is approximately equal to 28 inches or 0.7112 meters.
The archin was commonly used in measuring cloth, land, and building dimensions in Russia and neighboring regions. It roughly corresponds to the length of a forearm from the elbow to the tip of the middle finger, similar to the cubit.
Though obsolete today, the archin remains an important part of Russian historical measurements and appears in older legal and trade documents.
Summary:
1 archin ≈ 28 inches (0.7112 meters)
Used historically in Russia for textiles and land measurement
Based on the length of the forearm
Mostly of historical and cultural interest today
No conversions available for length.