Here is the passage in context from the King James Bible:
1 Samuel 13:1 Saul reigned one year; and when he had reigned two years over Israel,
1 Samuel 13:2 Saul chose him three thousand men of Israel; whereof
two thousand were with Saul in Michmash and in mount Beth-el, and a
thousand were with Jonathan in Gibeah of Benjamin: and the rest of the
people he sent every man to his tent.
There are two different versions of the ESV, so I will give you 1 Samuel 13:1 in both versions:
1 Samuel 13:1 ESV-UK "Saul was…[a] years old when he began to reign, and he reigned for… and two[b] years over Israel."
What in the world?! Can you imagined being called on to read this chapter out loud in front of the church? How do you even read that?
Here it is in the American version of the ESV:
1 Samuel 13:1 ESV "Saul lived for one year and then became king, and when he had reigned for two years over Israel,"
As you can see, it is completely different in the two versions of the ESV. So according to the American ESV, Saul was a one-year-old when he became king! The most amazing part of all is that he was already tall enough to be head and shoulders above the people (1 Samuel 10:23) at one year old! The ESV is looking more like the Weekly World News than the Bible.
The ESV is supposedly the choice of great Bible scholars, yet they are dumb enough to think that King Saul was one year old when he became king.