Question

97215*6, in this no what should we put in place of * to make it completely divisible by 11?

Answer 1

Condition for the Divisibility  of 11 is
difference of (sum of the odd digits & the even digits)= zero or multiples of 11
So the given number is  

  9 7 2 1 5 * 6

sum of the odd digit = 9+2+5+6  =  22
sum of the even digit  = 7+1+*    = 8 + *
so, 
                22 - (8 + * ) = 0 or multiples of 11
                    14 - *  =  0 or (11, 22, 33, 44.....)
                if  zero is taken
                   14 - * = 0   
                        *  = 14 but this not possible because we need only one digit.
                   14 - *  = 11
                          *  = 14 - 11
                         * = 3
so the missing number is 3