If 7845K854 is divisible by 11, then what is the value of K?
2024
If 7845K854 is divisible by 11, then what is the value of K?
- A.
6
- B.
9
- C.
7
- D.
8
Attempted by 16 students.
Show answer & explanation
Correct answer: B
Divisibility Rule for 11
A number is divisible by 11 if the difference between the sum of the digits in odd positions and the sum of the digits in even positions is either 0 or a multiple of 11.
Step-by-Step Calculation
Identify the positions (from right to left):
Number: 7 8 4 5 K 8 5 4
Positions:
Odd positions (1st, 3rd, 5th, 7th): 4, 8, 5, 8
Even positions (2nd, 4th, 6th, 8th): 5, K, 4, 7
Calculate the sums:
Sum of digits in odd positions = 4 + 8 + 5 + 8 = 25
Sum of digits in even positions = 5 + K + 4 + 7 = 16 + K
Find the difference:
Difference = (Sum of odd positions) - (Sum of even positions)
Difference = 25 - (16 + K)
Difference = 25 - 16 - K
Difference = 9 - K
Solve for K:
For the number to be divisible by 11, the difference must be 0 or a multiple of 11.
If 9 - K = 0, then K = 9.