The smallest 1-digit number to be added to the 6-digit number 489483 so that it is completely divisible by 11 is:

Correct option is D

Given:

Number: 489483​

Divisor: 11

Formula Used:

A number is divisible by 11 if the difference between the sum of digits at odd places and the sum of digits at even places is 0 or a multiple of 11. 

Solution: 

Sum of odd digit = 3 + 4 + 8 = 15

Sum of even place digit = 8 + 9 + 4 = 21

difference = 21 - 15 = 6 not multiple of 11 or 0 

Observing the digits we can see that if we add 6 in unit digit than 

Number became 489489​

Sum of odd digit = 9 + 4 + 8 = 21

Sum of even place digit = 8 + 9 + 4 = 21

Difference = 21 - 21 = 0 which makes the number divisible by 11 .

Thus, 6 is the smallest 1-digit number that makes the number divisible by 11.

Option (d) is right.