Question

The number of ways to select $2$ numbers from $0,1,2,3,4$ such that the sum of the square of the selected number is divisible by $5$ are (repetition of digits is allowed ).

• A. $9$
• B. $11$
• C. $17$
• D. $Noneofthese$

Answer 1

Answer: (A)

$9$

Consider unit digits of squares $0,1,4,9,6$

no. of ways of selecting any $2$ that sum up to give either $5$ or $0$ is

0+0

1+9

1+4

4+6

9+6

$Total=9$