The sum total of the Birth Year is used to calculate Kua Number. But the calculation is Different for Male and Females.

For Male
Take the Sum of Birth Year and subtract it from 11.
For example. – 1976 1+9+7+6= 23 = 2+3= 5
So, 11-5=6
Hence, 6 is the Kua Number for Male of this Birthdate.

For Female
Take the Sum of Birth Year and add the number 4 to it.
For example. – 1976 1+9+7+6= 23 = 2+3= 5
So, 5+4=9.
Hence, 9 is the Kua Number for Male of this Birthdate.