In the account of Samuel, it says: “And the Syrians fled before Israel; and David slew the men of seven hundred chariots of the Syrians, and forty thousand horsemen, and smote Shobach, the captain of their host, who died there.” (2 Samuel 10:18)
Whereas the book of the Chronicles report says: “But the Syrians fled before Israel; and David slew of the Syrians seven thousand men which fought in chariots, and forty thousand footmen, and killed Shophach the captain of the host.” (1 Chronicles 19:18)
There seems to be a “contradiction” here, for the first verse says 700 men but Chronicles says 7,000 men.
How can we explain this difference in accounts?
The explanation is simple as it just requires careful reading. The first verse says:
“… David slew the men of seven hundred chariots of the Syrians…”
The verse does not say that David killed 700 men, but men of seven hundred chariots. The verse does not give the number of men, but of chariots, that is, 700 chariots.
The second verse says:
“…David slew of the Syrians seven thousand men which fought in chariots…”
This verse however does not say how many chariots but 7000 men which fought in chariots. So the number of men who fought was 7000.
Taken together, these verses reveal that David killed 7000 men fighting in 700 chariots. That makes 10 men per chariot.
Of course, not all 10 men fought in a chariot back then in the war because it didn’t work out (regarding space). So, what they did was five teams of two men each. One soldier would drive and steer the chariot and the second would fight. Why five teams were formed, however, was simple. The chariot was the “tank” in war and they wanted to use it in the battlefield for as long as possible, because you could use it to storm to the front, attack and, in case of retreat, be able to drive back quickly. Now one of the five scenarios could happen.
Either one of the two warriors is injured (1), killed (2), exhausted (3), tired (4), or requires recovery (food) (5). It would therefore be problematic to leave the chariot standing. That’s why five teams have been formed per chariot so that they can switch among themselves at any time in one of the five scenarios mentioned above. In this way, it was guaranteed that the chariot always stays in the battle to gain an advantage over the enemy who is approaching on foot.
The differences between the books (Samuel/Kings/Chronicles) are not “Bible contradictions” but merely more information for the reader to get the full story and event.