Sieve

sieve.rb

def sieve(to)
    n = Array.new(to, true)

    for i in 2..Math.sqrt(to) do
        if n.at(i) == true
            j = i;
            while j*i < to do
                n[i*j] = false
                j += 1
            end
        end
    end

    for i in 2..to do
        if n.at(i) == true
            puts i
        end
    end

end

sieve(100)