《宋书·志·卷十三》
求下一个没日：数上加六十九，曰余上加三万四千四百四十二，日余满没法则减去没法在曰数上加一，就是下一个没。
求次没，加日六十九，日余三万四千四百四十二，余满没法从日，次没日也。
To calculate the next dark day: add sixty-nine, add thirty-four thousand four hundred and forty-two to the additional days. If the additional days reach the dark period, subtract the dark period and add one to the days, resulting in the next dark day.