In the diagram, all rows, columns and diagonals have the sum 12. What is the sum of the four corner numbers?
(A) 14
(D) 17
(B) 15
(E) 12
(C) 16

![](https://cdn.mathpix.com/cropped/2024_04_20_46ead6524a8d61e21c51g-097.jpg?height=220&width=222&top_left_y=1321&top_left_x=1426)
In the diagram, all rows, columns and diagonals have the sum 12. What is the sum of the four corner numbers?
(A) 14
(B) 15
(C) 16
(D) 17
(E) 12

![](https://cdn.mathpix.com/cropped/2024_04_20_748fdafcde2a47412608g-420.jpg?height=222&width=236&top_left_y=1491&top_left_x=1411)

## Solution

If we fill in the four corners in the indicated order the sum of the numbers at the corners is $4+3+4+5=16$. (This is, of course, not the only way to find the desired number. We could also have started by adding up along the centre column.)

![](https://cdn.mathpix.com/cropped/2024_04_20_748fdafcde2a47412608g-420.jpg?height=389&width=231&top_left_y=1795&top_left_x=1405)

ANSwER: (C)