Question

if the in numbers A 78 B is divisible by 55. then what is the value of A and B.

Answer 1

As the number is divisble by 55 , it should be divisble by both 11 and 5.
A number is divisible by 11 , if the alternating sum of digits in the number is divisible by 11.
so , A + 8 -7 - B is divisible by 11.
A - B + 1 is divisible by 11.
As , the number is divisible by 5 also , B is either 5 or 0.
If B = 5 ,
A - 4 is divisible by 11 , So , A must be 4( 0 is divisble by 11)
If B = 0 ,
A + 1 is divisble by 11 , A is a single digit , 10>A > 0
SO not possible

Hence , A = 4 , B = 5.