四百(よんひゃく)

四(よん) + 百(ひゃく). Both parts keep their normal shape.

Pronunciation

Only three of the hundreds change:

• 三百(さんびゃく): ひゃく → びゃく
• 六百(ろっぴゃく): ろく → ろっ, ひゃく → ぴゃく
• 八百(はっぴゃく): はち → はっ, ひゃく → ぴゃく

All the others, including 四百(よんひゃく), are regular.
The older reading しひゃく survives only in a few set expressions such as 四百四病(しひゃくしびょう) (the ills that flesh is heir to). For counting, always say よんひゃく.

Common collocations

• 四百(よんひゃく)字(じ)詰(づ)め原稿(げんこう)用紙(ようし): the standard 400-character manuscript sheet
• 四百(よんひゃく)メートル走(そう): the 400-meter dash