2 Chr 34:1

בֶּן־שְׁמוֹנֶ֥ה שָׁנִ֖ים יֹאשִׁיָּ֣הוּ בְמָלְכ֑וֹ וּשְׁלֹשִׁ֤ים וְאַחַת֙ שָׁנָ֔ה מָלַ֖ךְ בִּירוּשָׁלִָֽם׃

Josiah was eight years old when he became king, and he reigned in Jerusalem thirty-one years.