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