With or without water it can be used as a barrier, as an alternative for a fence.
A trench is a long narrow ditch.
Types and applications include:
... pair (17,296, 18,416) and the pair (9,463,584, 9,437,056). The pair (6232, 6368) are amicable, but they cannot be derived from this formula.
Amicable numbers hav ...
Kids.Net.Au - kids safe portal for children, parents, schools and