Zero to the zero power

[0, Complex(0, 0)].each {|n|
    say n**n
}

Output:

1
1

Taking the 0'th root of a number and raising it back to the zero power, we also get a 1:

say 0.root(0).pow(0)       # => 1
say ((0**(1/0))**0)        # => 1