Given: Six Digit Number = 1123x7 Concept used: Divisibility law of 9 ⇒ A number divisible by 9 if sum of its digit is divisible by 9. Calculation: 1123x7 is divisible by 9. Therefore, 1 + 1 + 2 + 3 + x + 7 ⇒ 14 + x If we put x = 4, then, the number become 18 which is divisible by 9. ∴ x = 4