40 (forty) is a positive integer following 39 and preceding 41. Its ordinal form is written "fortieth" or 40th.

Properties Edit

40 is an even composite number.

40 is the only number whose letters are in alphabetical order.

In googology Edit

In Greek-based number-naming systems, 40 is associated with prefix "tetraconta-", and with prefix "quadraginti-" in Latin systems.