Question

if 3!=3*2*1, calculate the score from 1*1! +2*2! +3*3! +...+9*9!

Answer 1

hint\[n\times n!=(n+1-1)\times n!=(n+1)!-n!\]

Answer 2

i don't understand

Answer 3

using mukushla hint :

1*1! = (1+1)! - 1!
2*2! = (2+1)! - 2!
so far :
(1+1)! - 1! + (2+1)! - 2!
2! - 1! + 3! - 2! = -1! + 3!
do you see the pattern ?