Question

Question 28

In the given question, fill in the blanks to make the statement true.

A four-digit number abcd is divisible by 11, if d + b = ___ or ___ .

Answer 1

a + c, 12(a + c)
We know that, a number is divisible by 11, if the difference between the sum of digits at odd places and the sum of its digits at even places is either 0 or a multiple of 11.
Hence, abcd is divisible by 11, if (d + b) - (a + c) = 0, 11, 22, 33, ......
$\Rightarrow$ d + b = a + c or d + b = 12 (a + c)