If the 9-digit number 5x79856y6 is divisible by 36, then what is the negative value of for the largest possible value of y, given x and y are natural numbers?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. -5.
The given number is divisible by 36. So, the number is divisible by both 4 and 9.
A number is divisible by 4 if its last two digits are divisible by 4.
So, y6 to be divisible by 4. The possible values of y are 1, 3, 5, 7, or 9.
The maximum value of y = 9
A number is divisible by 9 if the sum of its digits is divisible by 9.
The sum of digits = 5 + x + 7 + 9 + 8 + 5 + 6 + 9 + 6 = 55 + x [Taking, y = 9]
If x = 8 then 55 + x = 63 which is divisible by 9.
Now, = √25 = -5 or 5
Required value = -5 (Negative value required)