1*2*3*4*5*6*7*8*9*10
=2*3*4*5*6*7*8*9*10
=6*4*5*6*7*8*9*10
=24*5*6*7*8*9*10
=120*6*7*8*9*10
=720*7*8*9*10
=5040*8*9*10
=40320*9*10
=362880*10
=3628800
1*2*3*4*5*6*7*8*9*10
=2*3*4*5*6*7*8*9*10
=6*4*5*6*7*8*9*10
=24*5*6*7*8*9*10
=120*6*7*8*9*10
=720*7*8*9*10
=5040*8*9*10
=40320*9*10
=362880*10
=3628800