static long solve(String s) {
        BigInteger sum = BigInteger.valueOf(Character.getNumericValue(s.charAt(0)));
        for(int i=1;i<s.length();i++){
            sum = sum.multiply(BigInteger.valueOf(11)).add(BigInteger.valueOf(2).pow(i).multiply(BigInteger.valueOf(Character.getNumericValue(s.charAt(i)))));
        }
        return sum.mod(BigInteger.valueOf(1000000007)).longValue();
    }

Then all the seven subset numbers will be 

1)  (100*a +10*b + c ) 

2)  ( 10*b +c )

3)  (10*a + b) 

4)  (10*a + c )

5)  a

6) b

7)  c

--------------------------------------------------------------------
121 a  +  22 b + 4 c

2^0 * 11^2 * a  =  121 a

2^1 * 11^1 * b =   22 b

2^2 * 11^ 0 * c= 4 c

So , pattern we get .That's all . Now do code