Binary number representation, relying on the fact that 0.111111... is the sum of the geometric series 2 + 2 + 2 + ... which is 1. Binary numerals which neither terminate nor recur represent irrational numbers. For instance, Binary number In mathematics and digital electronics, a binary number is a number expressed in the base-2 numeral system or binary numeral system, which uses only two symbols: typically 0 (zero) and 1 (one). The base-2 numeral system is a positional notation with a radix of 2. Each digit is referred to as a bit. Because of its straightforward implementation in digital electronic circuitry
Contact binary (small Solar System body) Contact binary (small Solar System body) A contact binary is a small Solar System body that is composed of two bodies that have gravitated toward each other until they touch. This means contact binaries have odd shapes. Comet Churyumov–Gerasimenko and Comet Tuttle are most likely contact binaries. Asteroids suspected of being contact binaries include the unusually elongated 624 Hektor and the bilobated 216 Kleopatra and 4769 Castalia. 25143 Itokawa, which was photographed by the "Hayabusa" probe, also appears to be a contact binary which has resulted in an elongated, bent body. About 10–15% of near-Earth asteroids larger than 200 meters