5

5 (five) is a positive integer following 4 and preceding 6. Its ordinal form is written "fifth" or 5th.

Properties
5 is an. Since 10 is a multiple of 5, divisibility by 5 can be easily tested in the decimal system &mdash; multiples of 5 always end in 0 or 5. 5 is a :  + 1 = 5.

In googology
Some googologisms based on 5 are superpent, googolquinplex and quintoogol. 5 is the length of the Goodstein sequence starting with 3, which goes 3, 3, 3, 2, 1.

In Greek-based number naming systems, 5 is associated with prefix penta-, and with prefix quinti- in Latin systems.

Googological functions returning 5

 * Goodstein function: \(G(3)=5\)
 * Weak Goodstein function: \(g(3)=5\)
 * Laver table: \(q(3)=5\)
 * Weak tree function: \(\text{tree}(2)=5\)
 * Friedman's circle theorem: \(\text{Circle}(1)=5\)
 * simple subcubic graph number: \(\text{SSCG}(1)=5\)