2 Chronicles 36:9
Was Jehoiachin 8 years old, or 18 (per 2 Kings 24:8) when he ascended the throne? 18 is more likely, and is supported by one Hebrew mss., some LXX mss., and Syriac mss. Gleason Archer ( Encyclopedia of Bible Difficulties , 214-5) states: "A numerical system generally in use during the fifth century BC (when Chronicles was probably composed -- very likely under Ezra's supervision) features a horizontal stroke ending in a hook at its right end as the sign for "ten"; two of them would make the number "20". The digits under ten would be indicated by rows of little vertical strokes, generally in groups of three. Thus, what was originally written over one or more of these groups of short vertical strokes (in this case, eight strokes) would appear as a mere `eight' instead of `eighteen'". See our foundational essay on copyist errors for general background.
http://www.tektonics.org/copyisterrors.html
Another noted issue: 2 Kings 24:8 which states the regnal length as three months, whereas 2 Chr 36:9 states three months and ten days. The author(s) of Kings, from the reign of Rehoboam on through Zedekiah (at the end of 2 Kings), presents regnal lengths in round figures. For those whose regnal length was more than twelve months, and exact year figure was given. So, if I reigned 17 months as King of Judah, Kings would either say my reign was one year or two years, rounding off the months figure. For those whose regnal length was less than twelve months (Zechariah, Shallum, Jehoahaz, and Jehoiachin), the author lists their reigns in exact months. The only special case here is Zimri, whose regnal length was a scant 7 days. But the internal testimony of Kings is that round figures are being used. 2 Kings used round numbers, the Chronicler used an exact count here.
http://www.tektonics.org/TK-2CHR.html