五

五 (wǔ) is the cardinal number five. Like all Chinese numbers, 五 normally requires a measure word before a noun: 五个人 (five people), 五本书 (five books), 五个苹果 (five apples) — never 五人 or 五书 in standard Chinese. A few nouns skip the measure word as fixed units: 五块 (five kuai, money), 五点 (five o'clock), 五岁 (five years old), 五天 (five days), 五年 (five years). Culturally, 五 is a tidy 'middle' number — neither lucky nor unlucky in mainstream superstition, though it appears in 五行 (the Five Elements: metal, wood, water, fire, earth) and 五福 (the Five Blessings). The formal / anti-fraud written form used on checks and contracts is 伍.

Memory hook: 五 has an X inside two lines — five fingers, hand opened wide.