The Power Of 15

[Theboxer500]

I saw a man that figured out the power of 83 without a calculator and he said each number in a second. The guyz nickname is the human calculator. Now the weird thing is that this guy was not good at math in hight school. He slowly started to learn about math and got very good at it. He is from Germany, I think?

[kahea2018]

ah ok...

[mouseballus]

there are neck brackets that have nine squares with movable numbers 1 through 9 it is a puzzle and the object is to add them all to 15. One solution is shown here.