ABC:1 Chronicles 11

Verse 11
The ReasonProject lists the following as a Bible contradiction with the headline "How many men did the chief of David's captains kill?"

2 Samuel 23:8 These be the names of the mighty men whom David had: The Tachmonite that sat in the seat, chief among the captains; the same was Adino the Eznite: he lift up his spear against eight hundred, whom he slew at one time.

1 Chronicles 11:11 And this is the number of the mighty men whom David had; Jashobeam, an Hachmonite, the chief of the captains: he lifted up his spear against three hundred slain by him at one time.

There are two very likely answers to this problem.

Solution 1: Later Account
As pointed out by Bill Fortenberry, the lists were actually composed at two different times, so Bill suggests that 2 Samuel 23 is just a case of beating one's own record, as it were, surpassing his previous feat in battle

This solution is found in verse 1 of II Samuel 23. That verse begins with the phrase: 'Now these be the last words of David.' This tells us that the list in II Samuel 23 was compiled at the end of David's life. But when we read I Chronicles 11, we discover that this list encompasses the time period when 'David waxed greater and greater' (vs. 9). Thus the list in I Chronicles 11 was compiled early in David's reign, and the list in II Samuel 23 was compiled at the end of his reign.

-Bill Fortenberry, Increasing Learning

Solution 2: Two Different Individuals
Another solution, and in my opinion the more likely one, is that there are two different individuals being referred to. 1 Chronicles 11:11 specifically mentions Jashobeam the Hachmonite as the one who slays 300, and does not even mention Adino until v. 42 as "Adina the son of Shiza the Reubenite, a captain of the Reubenites, and thirty with him."

However, 2 Samuel 23:8 specifically says the 800 were slain by Adino, not Jashobeam. Confusion may be caused by the phrase "chief among the captains; the same was Adino the Eznite" but it is just saying that Adino was also one of the captains like Jashobeam, not that they were one and the same.

There are actually two groups of three mentioned between the chapters. There are "three mighties", captains of the armies, Jashobeam, Adino, and Eleazar. (1 Chr. 11:10-19,42; 2 Samuel 23:8-17) There is a lesser group of three, apparently David's personal guard, Shammah/Shammoth, Abishai, and Benaiah. (1 Chronicles 11:20-25,27; 2 Samuel 23:11-12, 20-23)