If a 10-digit number 6220x558y2 is divisible by 88, then the value of (5x + 5y) is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 20
For divisibility by 88, number should be divisible by 11 and 8 both.
6220x558y2 is divisible by 88
For divisible by 8 last 3 digit of the number (8y2) must be divisible by 8.
So, the value of y can be 3 or 7.
For divisibility by 11, difference of sum of digits at odd place and sum of digits at even place must be zero or divisible by 11.
So, (6 + 2 + x + 5 + y) - (2 + 0 + 5 + 8 + 2) = 0 or 11
Now, x + y– 4 = 0
x + 3 – 4 =0 (for y=3)
x = 1 ……digit cannot be negative
And,
x + 7 – 4 = 0 (for y = 7)
x = -3 ……digit cannot be negative
Hence,
We have x = 1 and y = 3
5x + 5y = 5 + 15 = 20