Custom validation in constant sum question.

Hi dipeshsingh
This thread might help. Please have a look.
PS: The above attached case is very similar to yours, you might do some changes in the provided custom code and you'll get the solution.

dipeshsingh,
If the question is the last in the block, then you can perform the calculation and terminate logic in the survey flow (replace QIDxx with actual question id):
Set Embedded Data:
ABDsum = $e{ q://QIDxx/ChoiceNumericEntryValue/1 + q://QIDxx/ChoiceNumericEntryValue/2 + q://QIDxx/ChoiceNumericEntryValue/4 }

Branch:
If Embedded Data ABDsum Is Less Than 50

End of Survey

Hi TomG

My question was not in the end of block by I did a similar thing. I created a additional text entry question to validate and terminate. BTW thanks :)