1 is an Arabic numeral.

1 is a natural number between 0 and 2.

1 is neither prime nor composite.

1 is the smallest positive integer.

Any number multiplied by (divided by) 1 equals the original number.

The first power and first root of any number are equal to the original number.

The greatest common factor of two prime numbers is 1.

Any sum of numbers 1 is a pair of prime numbers.

1 can be converted into any false fraction with the same numerator and denominator (not 0).

The factor of 1 has only itself and is a factor of any positive integer.

Any natural number is a multiple of 1

The reciprocal of 1 is 1 and the reciprocal is-1.

1 is the first 1 2 of Fibonacci series, and it is the number with the highest frequency in Fibonacci series.

The absolute value and n-th root of 1 are still 1.

The ratio of two equivalent infinitesimals (large ones) is 1.

When probability is expressed by classical probability, it means inevitable event.

Represents a perfect number.

Any degree of 1 is 1.

If any positive number is infinitely squared, the result will be close to 1.

1 is a rectangular number.

1 cannot be used as the radix of the carry system.

1 cannot be the base of logarithm.

In factorial operation, 0! = 1! = 1。

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 includes 0, 1, 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 first one is 0 and the last one is 4.

The complex number of 1 height.

The 1 th total is a hard number.

1 lucky number.

1 happy number.

1 is the number of even prime numbers.

The 1 th triangular 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(/.

0.999…= 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 .

1 is the Hegner number.