Life Gua For Male
Using year of Birth, add up the 4 digits of the year of birth
Reduce it to a single digit, then subtract by 11
The result will be your Gua number

For Example:
1978
1+9+7+8=25, 2+5=7, 11-7=4
4 is the Life Gua for the male born in 1978

Life Gua For Female
Using year of Birth, add up the 4 digits of the year of birth
Reduce it to a single digit, then plus 4, then reduce it to single digit is necessary
The result will be your Gua number

For Example:
2016
2+0+1+6=9, 9+4+13, 1+3=4
4 is the Life Gua for the female born in 2016

      1坎 Kan - North
      2坤 Kun - SouthWest
      3震 Zhen - East
      4巽 Xun - SouthEast
      5坤 男Male - Kun - SouthWest
      5艮 女Female - Gen - NorthEast
      6乾 Qian - NorthWest
      7兑 Dui - West
      8艮 Gen - NorthEast
      9离 Li - South

年命卦計算法

    男命 11-(公元出生年份四个数字互加),得数是两位数,再次互加,以餘数配卦
    例子 1989年出生男士, 1+9+8+9=27, 2+7=9, 11-9=2, 2为坤卦

    女命 4+(公元出生年份四个数字互加),得数是两位数,再次互加,以餘数配卦
    例子 2015年出生女士, 2+0+1+5=8, 4+8=12, 1+2=3, 3为震卦

*It is the same formula for who's born in before or after year of 2000