2 Chronicles 36:11

A son of twenty and one years is Zedekiah in his reigning, and eleven years he hath reigned in Jerusalem;

2 Kings 24:18-20

A son of twenty and one years is Zedekiah in his reigning, and eleven years he hath reigned in Jerusalem, and the name of his mother is Hamutal daughter of Jeremiah of Libnah,

Jeremiah 27:1

In the beginning of the reign of Jehoiakim son of Josiah, king of Judah, hath this word been unto Jeremiah from Jehovah, saying,

Jeremiah 28:1

And it cometh to pass, in that year, in the beginning of the reign of Zedekiah king of Judah, in the fourth year, in the fifth month, spoken unto me hath Hananiah son of Azur the prophet, who is of Gibeon, in the house of Jehovah, before the eyes of the priests, and all the people, saying,

Jeremiah 52:1-3

A son of twenty and one years is Zedekiah in his reigning, and eleven years he hath reigned in Jerusalem, and the name of his mother is Hamutal daughter of Jeremiah of Libnah.

Treasury of Scripture Knowledge

Summary

Zedekiah was one and twenty years old when he began to reign, and reigned eleven years in Jerusalem.

One and twenty

Bible References

One and twenty

2 Kings 24:18
A son of twenty and one years is Zedekiah in his reigning, and eleven years he hath reigned in Jerusalem, and the name of his mother is Hamutal daughter of Jeremiah of Libnah,
Jeremiah 52:1
A son of twenty and one years is Zedekiah in his reigning, and eleven years he hath reigned in Jerusalem, and the name of his mother is Hamutal daughter of Jeremiah of Libnah.