2 Samuel 10:18 (New International Version)
"18 But they fled before Israel, and David killed seven hundred of their
charioteers and forty thousand of their foot soldiers. [a] He also struck down
Shobach the commander of their army, and he died there."
"1 Chronicles 19:18 (New International Version)
18 But they fled before Israel, and David killed seven thousand of their
charioteers and forty thousand of their foot soldiers. He also killed Shophach
the commander of their army."
One theory is the bigger number is due to scribal error in Hebrew with the
dots that indicated how many thousands and were put over letters.
http://www.apologeticspress.org/articles/542
http://www.carm.org/bible-difficulties/joshua-esther/how-many-charioteers-were-killed-700-or-7000
Another theory is that the Hebrew word eleph can mean thousand or unit (as in
family, tribe, clan, cattle, etc.--Judges 6:15; 1 Sam.10:19-21,18:51, etc.)
700 charioteers could be referred to in the other verse as 7 military units of
charioteers. This theory holds that a scribe would be unlikely to to confuse
the number 100 with 1,000. See other examples of the same difference at the next
link.
http://www.specialtyinterests.net/hebrew_numbers.html
http://docs.google.com/gview?a=v&q=cache:rhYmbVqRG80J:www.bsmi.org/download/kimble/Alleged%2520Discrepancies%2520in%2520the%2520Bible%2520-%2520Kimble.pdf+2+Samuel+10:18+1+Chronicles+19:18&hl=en&gl=us&pid=bl&srcid=ADGEESj6splPzMNloLsHkxjchXH04VUsS2W9lrTHA0C-hZFDY9C8AqzlfdmQAu540yFewETkXcLkihSufMJhm_82PizVwUJWnVEF8TqOSZ6pduwSsafzZuhbeuLuBVajWFRQ9DKsMqlz&sig=AFQjCNFg66-c6ebVbDf8e3BgSPVx1MwK6w
Another theory is that David got the credit as the leader for the charioteers
his army killed, and both passages in the Greek Septuagint indicate that 1,000
chariots and 7,000 horsemen were captured. The smaller number in Hebrew could
refer to part of the larger number--those who were killed outright in the
battle, and the bigger number in later Hebrew could add those who died later as
a result of the battle. The later deaths could be due to a forceful stop to an
uprising on the part of those captured and/or due to the fact that in most wars
there are greater deaths from wounds leading to fatalities or fatal illness apart
from the battlefield. The later Greek then used that number for both passages.
(I made the latter part of the last one up myself. Worse than a quick death
in those wars was to linger and develop some form of ailment, like rickets, then
die, which was all the more terrifying to the townspeople.)