Arabic and Indian figures. Are natural numbers and integers between 0 and 2. The smallest positive odd number. The smallest positive integer (because "0" is neither positive nor negative). It is neither a prime number (prime number) nor a composite number. Any number divided by 1 is equal to the original number. Any number multiplied by 1 is equal to the original number. The greatest common factor of two prime numbers is 1. It can be converted into any false fraction with the same numerator and denominator. The factor of 1 has only itself and is the common factor of any positive integer. The reciprocal of 1 is 1 and the reciprocal is-1. It is 1 2 of Fibonacci sequence, and it is the number with the highest frequency in Fibonacci sequence. The absolute value of 1 is still 1. The nth root of 1 is still 1. The ratio of two equivalent infinitesimals is 1. When probability is expressed by classical probability, it means inevitable occurrence or inevitable event. Represents a perfect number. Any number whose power is 1 is an original number. Any degree of 1 is 1. If any number is infinitely squared, the result is close to 1. 1 is 1, 3, 37 and 40 bits of the fractional part of pi. The number of rectangles. Cannot be used as the basis of the carry system. You can't do the base of logarithm. In factorial, 0! = 1! = 1。 In probability theory, the probability of random events in any sample space is defined as. In geometry, the radius of unit circle and unit ball is 1. Euler formula establishes the relationship between the five most important constants in mathematics in the simplest way. The formula contains 0, the base e of natural logarithm, pi and imaginary unit i of complex number. The product of two reciprocal is 1. The second square number. The complex number of 1 height. The 1 th total is a hard number. 1 lucky number. 1 happy number. The number of even prime numbers. The 1 th triangular number. In probability theory, the probability of random events in any sample space is defined as 1. Euler's identity eiπ+ 1=0 links five important constants in mathematics in a simple way. The formula includes 1 0, the base e of natural logarithm, pi and imaginary unit i of complex number. 1 is the deficit of 1. 1 in any radix system is written as 1, that is,1(2) =1(3) =1(4) =1(8) =1(/. 0.9999999999……= 1。 Batuwan series items 1, 2 and 3. Any nonzero number with a power of 0 is equal to 1, that is, a? = 1，a≠0 .