What is the least number that must be added to $4042$ to make it a perfect square?

The difference between a two-digit number and the number obtained by interchanging the digits is $36$. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is $1:2$?

Two numbers differ by $5$. If their product is $336$,then the sum of the two numbers is

Two numbers are such that the ratio between them is $3:5;$ but if each is increased by $10,$ the ratio between them becomes $5:7.$ The numbers are

The product of two numbers is $45$ and the sum of their squares is $106$. The numbers are

$(2+\sqrt{5})^{2}=?+4 \sqrt{5}$