\[\binom{13}{6} / \binom{52}{6}\] = 1716 / 20358520 = 0.000084
\[\binom{4}{3}\binom{4}{2}\binom{4}{1} / \binom{52}{6}\] = 4x6x4 / 20358520 = 0.000047
\[\binom{4}{2} . \left (\binom{13}{3}\binom{13}{3}/ \binom{52}{6} \right )\] = 6 x ( 286 x 286 / 20358520 ) = 0.0241