Julia doesn't just let the user define Unicode operators, but also has many of them predefined, such as the "less than or equal" and "not equal" you mentioned. The ÷ division operator is also part of the standard library, but doesn't have the same semantics as the "plain ASCII" division operator:
5.0 / 3.0 == 1.666...
5 / 3 == 5//3 # a rational number
But ÷ only returns the quotient, just like dividing integers in C:
5 ÷ 3 == 1
5.0 ÷ 3.0 == 1.0
Square roots are also available (as an operator): √5 == 2.236...