In some countries, the number 20 is used as an index in measuring visual acuity. 20/20 indicates normal vision at 20 feet, although it is commonly used to mean "perfect vision" in countries using the …

Middle English, from twenty, adjective, from Old English twēntig, noun, group of 20, from twēn- (akin to Old English twā two) + -tig group of 10; akin to Old English tīen ten — more at two, ten

The meaning of the number 20: How is 20 spell, written in words, interesting facts, mathematics, computer science, numerology, codes. Phone prefix +20 or 0020. 20 in Roman Numerals and images.

Your guide to the number 20, an even composite number composed of two distinct primes. Mathematical info, prime factorization, fun facts and numerical data for STEM, education and fun.

Welcome to “About The Number 20” – a fascinating exploration of the number twenty and its significance in various fields. Here, you will discover the diverse roles of 20 in mathematics, science, …

Properties of 20: prime decomposition, primality test, divisors, arithmetic properties, and conversion in binary, octal, hexadecimal, etc.

Jan 4, 2014 · Watch the official 20/20 online at ABC.com. Get exclusive videos, blogs, photos, cast bios, free episodes