In this problem, a number will be given.

starting with the first digit, keep on adding all subsequent digits till the state (even or odd) of the sum of the digits is opposite to the state of the first digit.

Continue this way till the last digit of the number is reached.

Concatenate all the sums to generate the new number.

 for example, n=74561. 
 we start with 7(odd);  7+4==11(odd);  11+5=16(even);    y=16
 remaining     6(even); 6+1=7(odd);                      y=167