your answer is not appropriate. Pl go through question again.

Ohh Sorry I didn't see the year. For Year 2016, Subject - wise cutoff was different as per Category.For general the minimum subject wise  cutoff was 13 and aggregate marks was 75.For OBC the minimum subject wise  cutoff was 12 and aggregate marks was 67.For ST and SC  and all other categories ,the minimum subject wise  cutoff was 07 and aggregate marks was 38.You were saying It Should be 12 instead of 13.Cutoff is based on lot of factors. It not just based on some set of rules or on one state. To Specify a cutoff The board thinks about whole country candidates. So, There must be some factor that general cutoff has to be 13 and obc 12.Hope you get it now.

Thanks  but my point of concern was that 10% of 124 comes to 12.4 and therefore cut off should be 12 and not 13.

As per rounding rules, any decimal number below .5 will be floored and above is ceiled.
For example 12.4 is rounded to 12.
12.5 then it will be 13