Math Puzzle 4.
KEEP IT EVEN !
Take 16 small objects (for example coins, magnets, pieces of paper, etc.) and put them in four rows of 4 as it shown on the right.
Remove 6, leaving an even number of objects in each row and each column.
Try to find as many solutions as many you can.
After you get bored with removing 6 pieces, try to remove 10 pieces.