This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

40 years

2 Kings 12:1 View context

In the seventh year of Jehu Jehoash began to reign; and forty years reigned he in Jerusalem. And his mother's name [was] Zibiah of Beer-sheba.

16 years

2 Kings 13:10 View context

In the thirty and seventh year of Joash king of Judah began Jehoash the son of Jehoahaz to reign over Israel in Samaria, [and reigned] sixteen years.