If the 7-digit number 2y6810x is divisible by 88, then what is the value of the product of x and y?
- A20
- B35
- C10
- D15
Solution & Step-by-step Explanation
A number is divisible by 88 if it is divisible by both 8 and 11.
Divisibility by 8:
The last three digits of the number (10x) must be divisible by 8.
Testing possible values for the single digit x:
If x=4, 104÷8=13 (perfectly divisible).
Thus, x=4.
The number becomes 2y68104.
Divisibility by 11:
Sum of digits at odd positions: 2+6+1+4=13
Sum of digits at even positions: y+8+0=y+8
The difference must be a multiple of 11 or 0:
13−(y+8)=5−y
For this to equal 0, y must be 5.
Now, we calculate the product of x and y:
Product=x×y=4×5=20
Divisibility by 8:
The last three digits of the number (10x) must be divisible by 8.
Testing possible values for the single digit x:
If x=4, 104÷8=13 (perfectly divisible).
Thus, x=4.
The number becomes 2y68104.
Divisibility by 11:
Sum of digits at odd positions: 2+6+1+4=13
Sum of digits at even positions: y+8+0=y+8
The difference must be a multiple of 11 or 0:
13−(y+8)=5−y
For this to equal 0, y must be 5.
Now, we calculate the product of x and y:
Product=x×y=4×5=20