Question 13
KenKen is a Japanese number puzzle. The 4×4 square is divided into cages by thick lines. Each cage has a target number and an operation. Examples: 7+ means that all numbers in the cage sum to 7; 2− means that the difference of its two numbers is 2; 2÷ means that the quotient of its two numbers is 2; 4× means that the product of all its numbers is 4. Fill the grid with 1, 2, 3, 4 so that every row and every column contains each number once and all cage conditions hold. What number belongs in the starred cell?
