**Yoash** son of Yehoachaz became king over Yisrael in year 3098, the 37th year of Yoash king of Yehudah, and he reigned 16 years. According to the calculation of the verses, since Yehoachaz became king in the 22nd year of Yoash king of Yehudah and reigned 17 years, the end of Yehoachaz's reign and the beginning of Yoash's reign over Yisrael should be in the 40th year of Yoash king of Yehudah, or at least the 39th, but Scripture says the 37th year of Yoash.
Rashi wrote (Melachim II beginning of chapter 12) that this verse is proven wrong from two sides and I have not found a solution for it. The Radak resolved that Yoash reigned during his father Yehoachaz's lifetime for 2 years. And it seems that among the kings of Yisrael, incomplete years were counted as complete years (see year 82), and so Rashi himself writes at the end of chapter 22. [Tzeda (see year 3464 for what is written in the name of Tzeda)].