Question 72163
6!/2!4! * 5!/4!1! is equivalent to 
{{{((6*5*4*3*2*1)/((2*1)(4*3*2*1)))*((5*4*3*2*1)/((4*3*2*1)(1)))}}}
{{{((6*5*highlight(4*3*2*1))/((2*1)*(highlight(4*3*2*1))))*((5*highlight(4*3*2*1))/(highlight(4*3*2*1)(1)))}}} Notice how there are repeating terms of 4*3*2*1
{{{((6*5*cross(4*3*2*1))/((2*1)*(cross(4*3*2*1))))*((5*cross(4*3*2*1))/(cross(4*3*2*1)(1)))}}} These terms cancel out.
{{{((6*5)/(2*1))*(5/1)}}}Now just multiply and divide as you normally would
{{{(6*5*5)/(2*1*1)}}}
{{{150/2}}}
{{{75}}}