256! / (256-2)! / 256^2 = 0.00390625  or 0.4%

##</code><code>##

    0.00390625^2 = 0.0000152587890625 or 0.0015%

##</code><code>##

    65536! / 65534! / 65536^2 = 0.0000152587890625 or 0.0015%

##</code><code>##

    0.0000000002328 or 0.000000023%