All About One

• The number 1 is the least counting number.

• The number 1 is a cardinal number. The first for 1 is an ordinal number.

• 1 is the smallest triangular number.

• 1 is the smallest Fibonacci number.

• 0! = 1.

• 1 is neither prime nor composite.

• In Latin 1 is called Onus.

• Concurrent lines meet at one point.

• Product of reciprocals is 1.

• The number 1 is the only number that does not change any number by multiplication or when used as a divisor.