Question 549841
(n!)/(r!(n-r)!)


(15!)/(7!*(15-7)!)


(15!)/(7!*8!)


(15*14*13*12*11*10*9*8!)/(7!*8!)


(15*14*13*12*11*10*9)/(7!)


(15*14*13*12*11*10*9)/(7*6*5*4*3*2*1)


(32432400)/(5040)


6435



So 15 C 7 = 6435