If the three-digit number 6\(x\)8, where \(x\) is the tens digit, is divisible by 9, what is the value of \(x\)?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4
A number is divisible by 9 when the sum of its digits is divisible by 9.
Digit sum \(=6+x+8=14+x\)
\(x\) is a digit from 0 to 9, so \(14+x\) lies between 14 and 23; the only multiple of 9 there is 18
\(14+x=18\), so \(x=4\)
Check: \(648=9\times72\). The value of \(x\) is 4.