C4 12 =C8 12 теперь -тендиги

[latex]C_{12} ^{4} = \frac{12!}{4!*8!} =C _{12} ^{8} = \frac{8!}{8!*4!} = \frac{8!*9*10*11*12}{4!*8!} = \frac{9*10*11*12}{1*2*3*4} = \frac{3*5*11*3}{1} =495[/latex]