STUDY / OBJECTIVE
Distinguish sequence, counting, parity and the time unit being labeled.
01 / STUDY
A sequence and a date are separate questions
The cycle first provides repeating labels. Knowing a label's position does not identify a calendar date. That requires a reliable reference date, time unit and counting method. The same pair recurs in different rounds, so preserve a larger temporal context.
02 / STUDY
Position numbers and steps moved
A table usually numbers positions one to sixty, while calculations often start at zero. With Jia-Zi at index zero, one step reaches Yi-Chou at index one. Inclusive counting calls these items one and two. Both conventions work, provided the record never switches between them silently.
03 / STUDY
Pairs absent from the cycle
Synchronous movement keeps the stem and branch positions at matching parity. Although arbitrary pairing gives 120 possibilities, this procedure visits only sixty. When a pair is absent, examine transcription, indexing and the material's purpose before silently replacing it with a nearby valid pair.
WORKED EXAMPLE
Check the sequence before attaching a unit
The exercise starts at Jia-Zi and moves twelve steps; no actual date is specified.
Twelve stem steps equal one full round plus two, reaching Bing.
Twelve branch steps complete a round and return to Zi. The resulting pair is Bing-Zi.
This is position thirteen in the table. Record twelve sequence steps, without labeling them years or days.
A step count becomes a time interval only when the input unit is established.
PRACTICE / REFLECTION
Exercises and answers
01Why do neither ten nor twelve steps reset both sequences?
Read the explanation
Ten resets the stems only; twelve resets the branches only. A joint return requires a multiple of both, with sixty the smallest positive value.
02Can “Jia-Zi day” identify a Gregorian date by itself?
Read the explanation
No. The label repeats. Supply a date range and reliable calendar correspondence, retaining alternatives when the evidence is incomplete.
A distinction to retain
Year, month, day and hour labels cannot be converted into one another with this table alone; each application has additional origins and boundaries.
Unit output
Three forward/backward traces, an explanation of an invalid pair and an input card stating its time unit.
REFERENCES
Reading references
Table 2 · the sixty-pair cycle
Checks sequence order; this unit does not convert actual dates into stem-branch designations.References reviewed: 2026-10-24. Examples, record templates and explanations are editorial teaching material. Fictional inputs are not historical events or efficacy evidence. Citations imply no affiliation.
SEQUENCE / PRACTICE
The sixty-pair cycle, step by step
Place the ten stems and twelve branches in their fixed orders. Begin at Jia and Zi, moving both sequences by one place at each step and wrapping each independently. The resulting sixty pairs can be checked against Table 2 in the Hong Kong Observatory reference.
The first joint return takes the least common multiple of 10 and 12: sixty steps. Odd positions pair with odd positions, and even positions pair with even positions. An arbitrary stem and branch therefore need not form a pair in this sequence.
Positive steps move forward; negative steps move backward. Zero keeps the origin. Range: −9999 to 9999. The origin is not counted as a step.
癸亥 + 1 → 甲子
Ten stems
- 1甲
- 2乙
- 3丙
- 4丁
- 5戊
- 6己
- 7庚
- 8辛
- 9壬
- 10癸
Twelve branches
- 1子
- 2丑
- 3寅
- 4卯
- 5辰
- 6巳
- 7午
- 8未
- 9申
- 10酉
- 11戌
- 12亥
Calculation trace
Table positions run from 1 to 60; calculation indices run from 0 to 59. Keep the remainder in 0–59, then add 1 to recover the table position.
- Starting position
- 60 − 1 = 59
- Steps to move
- 59 + (1) = 60
- mod 60
- 60 = 60 × (1) + 0
- Table position
- 0 + 1 = 1 · 甲子
The sixty-pair cycle
A gold outline marks the origin; dark green marks the result.
- 01甲子Jiǎ–Zǐ
- 02乙丑Yǐ–Chǒu
- 03丙寅Bǐng–Yín
- 04丁卯Dīng–Mǎo
- 05戊辰Wù–Chén
- 06己巳Jǐ–Sì
- 07庚午Gēng–Wǔ
- 08辛未Xīn–Wèi
- 09壬申Rén–Shēn
- 10癸酉Guǐ–Yǒu
- 11甲戌Jiǎ–Xū
- 12乙亥Yǐ–Hài
- 13丙子Bǐng–Zǐ
- 14丁丑Dīng–Chǒu
- 15戊寅Wù–Yín
- 16己卯Jǐ–Mǎo
- 17庚辰Gēng–Chén
- 18辛巳Xīn–Sì
- 19壬午Rén–Wǔ
- 20癸未Guǐ–Wèi
- 21甲申Jiǎ–Shēn
- 22乙酉Yǐ–Yǒu
- 23丙戌Bǐng–Xū
- 24丁亥Dīng–Hài
- 25戊子Wù–Zǐ
- 26己丑Jǐ–Chǒu
- 27庚寅Gēng–Yín
- 28辛卯Xīn–Mǎo
- 29壬辰Rén–Chén
- 30癸巳Guǐ–Sì
- 31甲午Jiǎ–Wǔ
- 32乙未Yǐ–Wèi
- 33丙申Bǐng–Shēn
- 34丁酉Dīng–Yǒu
- 35戊戌Wù–Xū
- 36己亥Jǐ–Hài
- 37庚子Gēng–Zǐ
- 38辛丑Xīn–Chǒu
- 39壬寅Rén–Yín
- 40癸卯Guǐ–Mǎo
- 41甲辰Jiǎ–Chén
- 42乙巳Yǐ–Sì
- 43丙午Bǐng–Wǔ
- 44丁未Dīng–Wèi
- 45戊申Wù–Shēn
- 46己酉Jǐ–Yǒu
- 47庚戌Gēng–Xū
- 48辛亥Xīn–Hài
- 49壬子Rén–Zǐ
- 50癸丑Guǐ–Chǒu
- 51甲寅Jiǎ–Yín
- 52乙卯Yǐ–Mǎo
- 53丙辰Bǐng–Chén
- 54丁巳Dīng–Sì
- 55戊午Wù–Wǔ
- 56己未Jǐ–Wèi
- 57庚申Gēng–Shēn
- 58辛酉Xīn–Yǒu
- 59壬戌Rén–Xū
- 60癸亥Guǐ–Hài
Four checks of understanding
01 · Move one step forward from position 60, Gui-Hai. Where do you arrive?
Reference explanation
Position 1, Jia-Zi. Gui wraps to Jia and Hai wraps to Zi. This identifies a sequence position; no year, month, day or hour has been assigned.
02 · Do one backward step and 59 forward steps from Jia-Zi reach the same pair?
Reference explanation
Both reach position 60, Gui-Hai. Their paths differ by one full cycle. Equal endpoints do not mean equal distances, so retain the starting point and step count.
03 · Why does Jia-Zi advanced by ten steps keep Jia but lose Zi?
Reference explanation
The ten-stem sequence completes a round, while the twelve-branch sequence reaches Xu. The result is position 11, Jia-Xu. Both sequences return together only after a common multiple of 10 and 12 steps.
04 · How does the tenth item counted from Jia-Zi differ from moving ten steps from Jia-Zi?
Reference explanation
Counting Jia-Zi as item one requires nine moves to reach item ten, Gui-You. Moving ten steps reaches position eleven, Jia-Xu. Establish the counting convention before applying a rule.
Record the starting pair, position, step count, counting convention and result. This lab handles sequence relations; converting an actual date also requires a calendar, a reference date and boundary conventions.
Sequence checked 2026-10-24. Calculations, interaction and exercises are editorial teaching material; they do not calculate civil dates or natal charts.
Next: calendars and solar terms →Personal study record; not a grade, assessment or credential.
Connected study paths
Calendars: cycles, terms and boundariesCosmic boards: objects and proceduresEditorial study material · 2026-10-24
