User blog comment:Deedlit11/Bignum Bakeoff appetizer/@comment-5529393-20140922175020/@comment-2033667-20140923043959

And some micro-optimizations just for kicks (still 100)

i = 9 << 99999, b = 3; B(x,y) {return y && y % b * pow(-~b, B(0,x)) + B(-~x, y/b);} main {while(i = ~-B(0,i)) -~b; return b;}