What Passover song asks 'Who knows one?' in Hebrew?

The Passover song that asks “Who knows one?” in Hebrew is Ehad Mi Yodea.

Ehad Mi Yodea, also written Echad Mi Yodea, is a cumulative song in the Haggadah. Each verse asks who knows a particular number, beginning with one and building upward. The answers connect numbers to Jewish beliefs and teachings, including one God, two tablets, three patriarchs and the five books of Moses.

The song’s structure makes it both a memory game and a teaching device. By the final verse, singers recite the entire sequence in reverse order, often with lively repetition. Families and communities may sing it in different melodies or languages, including Yiddish, Ladino and Judeo-Arabic.

According to the Encyclopaedia Judaica summary on the article, the song first appears in Ashkenazi Haggadahs in the 16th century and may have originated in Germany in the 15th century. Ehad Mi Yodea is sometimes confused with Chad Gadya because both are cumulative songs performed at the Seder, but Chad Gadya tells a chain-of-events story about a goat.