Hook length formula

[westin]

Hi,

I like to understand how this hook length formula work.



I think the hook is based on above (taking the summation for the number of cells right and down for each). However, I don't understand why x1 > x 2 > x 3 > x4 > x5 > X6 can come out to a rectangle in order to calculate the hook for each box. I am very new to this formula. I did watch the youtube [Shapes and Hook Numbers - Numberphile]

but I don't quite get how this problem can use this rectangle (box) to get the hooks. By the way, I am not 100% sure that this is the right shape to get the hooks, but at least it matches the denominator. Again thank you very much for the help!!! as always!!!