Question

Which of the following numbers is divisible by 11?​

Answer 1

Step-by-step explanation:

If that is divisible by 11, so is the original number. So, for instance, 2728 has alternating sum of digits 2 – 7 + 2 – 8 = -11. Since -11 is divisible by 11, so is 2728. Similarly, for 31415, the alternating sum of digits is 3 – 1 + 4 – 1 + 5 = 10.

Answer 2

Given:

Which of the following numbers is divisible by 11?​

Solution:

Know that, if the difference between the sum of the digits at the odd and even places equals 0 or divisible by 11, then the number is divisible by 11.

e.g., take a number - 764852

Find the sum of the digits at odd places (from the left),

$= 7 + 4 + 5\\ = 16$

Find the sum of the digits at even places,

$= 6 + 8 + 2\\ = 16$

Notice that the difference between the sum of the digits at odd and even places is 0.

$= 16 - 16\\=0$

Hence, 764852 is divisible by 11.