Jīn Sì Jú

海中金, 劍峰金, 白蠟金, 沙中金, 金箔金 and 釵釧金 are the six metal names, each covering two stem-and-branch pairs in the 納音 song. In a 丙 or 辛 year the count begins at 庚寅, so a 命宮 at 午 has the stem 甲, and 甲午 is 沙中金, which yields 金四局. The calculator treats the name as a filing label for the 命宮's pair and gives the bureau no quality of metal in the ordinary sense.

Four as the divisor means the verse jumps in larger steps: day one at 亥, day two at 辰, then three palaces forward and one back as it proceeds. The calculator reaches those same palaces by arithmetic. Day one needs three added to reach four, the quotient of one sits at 寅, and an odd addition steps back three to 亥. One entry in the Wikisource table, the thirtieth at 亥, is missing, and the arithmetic restores it.

Four is the starting age the first ten-year period carries in this bureau, inferred from the phrase 四岁 in the verse. The default chart starts it at the 命宮, and 紫微斗數全書 starts it one palace off. The 長生 stages for metal begin at 巳, by the book's list and in the calculator alike.