Eleven (11) is a positive integer one more than 10 and one less than 12.


11 is the fifth prime number (between 7 and 13). It is a member of a twin prime pair with 13.

11 is the first prime that isn't a Mersenne exponent, since 211-1 = [[2047] = 23*89.

11 is the fifth Lucas number, between 7 and 18.

In googology

In Greek-based number-naming systems, is associated with prefix "endeka-", and with prefix "undec-" in Latin systems.

Wiki user Denis Maksudov calls this number zeralum, and it's equal to f0(10) using the fast-growing hierarchy.[1]

There are several methods to test for divisibility by 11. The easiest is to alternately add and subtract digits, starting from the left, and starting at a subtraction. So 429 is aa multiple of 11 since 4-2+9 = 11. Another way is to add groups of two digits, starting from the right.

Cite error: <ref> tags exist, but no <references/> tag was found
Community content is available under CC-BY-SA unless otherwise noted.