Question 20
In this $4 \times 4$ Ken Ken, bold borders define cages labeled with a target and operation. For example, $7$+ means sum $7$; $2$− difference $2$; $2 \div$ quotient $2$; $4 \times$ product $4$. Fill each row and column with $1 \text{--} 4$ once each and satisfy every cage. What number is in the ★ cell?
