humanize-number.rb

class Numeric
    Q = ["B", "K", "M", "G", "T", "P", "Z"]

    def humanize
        index = ( (Math.log(self)/Math.log(10-10**-12)).to_i / 3 ).to_i # to_i to round down
        return [ self/10.0**(index*3), Q[index] ].join
    end
end

for i in 0..20 do
    puts (10**i).humanize
end

for i in 1..6 do
    puts (10**(i*3)-1).humanize
end

puts (60000*60000*8).humanize # sizeof double array[60000][60000] in C;