Using any combination of function (multiplication, addition, subraction, square root, etc) how can 7, 1, 9, 10 equal 4?
Us the following operations: (7 - 1)*9 + 10 = 6*9 - 10 = 54 + 10 = 64 to get 64.
Now take the square root twice to get 4.
i.e. Sqrt(sqrt((7 - 1)*9 + 10)) = 4