《宋书·志·卷十二》
求下一月：在大余上加二十九，小余上加二千四百一十九，小余如满曰法则减去曰法并在大余上加一，用前面所述的方法可得到下一个月朔日的干支。
求次月，加大余二十九，小余二千四百一十九，小余满日法从大余，命如前，次月朔日也。
To calculate the next month: add twenty-nine to the greater remainder and 2,419 to the smaller remainder. If the small remainder is full of days, subtract the days and add one to the greater remainder. Use the method described above to find the celestial stem and branch for the first day of the next month.