help me with this amazing problem. i have it in a doc file as i dont have paint
You will end up eight distinct numbers $\displaystyle a,~b+8,~c+16,~d+24,~e+32,~f+40,~g+48,~h+56$.
Each of a,b,c,d,e,f,g,h is distinct and between 0 & 9.
So the sum $\displaystyle a+b+c+d+e+f+g+h=36$
What is $\displaystyle \sum\limits_{k = 1}^7 {8k} = ?$