Two readings, two traditional characters, one simplified shape. As 干 (1st tone) it covers "dry / empty / sworn" — written 乾 in traditional script. As 干 (4th tone) it means "to do / trunk / cadre" — written 幹. The 1956 reform merged both into 干, plus the original native shield 干. Same simplified glyph, three historical sources.
culture
The 干 reading is also one of the ten heavenly stems (天干): the cycle 甲乙丙丁戊己庚辛壬癸. Paired with the twelve earthly branches it produces the 60-year sexagenary cycle still used for traditional dates and astrology.
Components
pictograph
干gān
shield; dry
Pictograph of a forked weapon used as both spear and shield — the two top horizontals are the prongs, the central vertical is the haft. Kangxi radical #51. The modern simplified 干 conflates three originally separate characters: the native shield 干, traditional 乾 ('dry'), and traditional 幹 ('trunk / to do').
Filed under radical 十 (shí, #24) by convention. 十 is not a separate component in 干, so no strokes are highlighted.
