Question 153917
<font size = 6 color = "red"><b>Edwin's solution:</pre></font></b>
<pre><font size = 4 color = "indigo"><b>
{{{20!/(2!18!) = (20*19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1)/((2*1)(18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1))}}} =

{{{20!/(2!18!) = (20*19*cross(18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1))/((2*1)(cross(18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1)))}}}

{{{20!/(2!18!) = (20*19)/(2*1) = 380/2 = 190}}}

Edwin</pre>