The Ten Commandments is often shown as a nice list with ten short statements, whereas in the Bible it exists as a long block of text in Exodus 20:2–17 and Deuteronomy 5:6–21. For reference:
Exodus 20:2-17 (HCSB)
2 I am the LORD your God, who brought you out of the land of Egypt, out of the place of slavery.
3 Do not have other gods besides Me.
4 Do not make an idol for yourself, whether in the shape of anything in the heavens above or on the earth below or in the waters under the earth. 5 You must not bow down to them or worship them; for I, the LORD your God, am a jealous God, punishing the children for the fathers' sin, to the third and fourth [generations] of those who hate Me, 6 but showing faithful love to a thousand [generations] of those who love Me and keep My commands.
7 Do not misuse the name of the LORD your God, because the LORD will punish anyone who misuses His name.
8 Remember to dedicate the Sabbath day: 9 You are to labor six days and do all your work, 10 but the seventh day is a Sabbath to the LORD your God. You must not do any work—you, your son or daughter, your male or female slave, your livestock, or the foreigner who is within your gates. 11 For the LORD made the heavens and the earth, the sea, and everything in them in six days; then He rested on the seventh day. Therefore the LORD blessed the Sabbath day and declared it holy.
12 Honor your father and your mother so that you may have a long life in the land that the LORD your God is giving you.
13 Do not murder.
14 Do not commit adultery.
15 Do not steal.
16 Do not give false testimony against your neighbor.
17 Do not covet your neighbor's house. Do not covet your neighbor's wife, his male or female slave, his ox or donkey, or anything that belongs to your neighbor.
If I were given the above text without paragraphs nor verse markers (which are a later addition), I'd have trouble spotting how it should be divided to exactly ten commandments. This might be a reason that there are multiple "competing" divisions.
The different divisions that I know of are (adapted from a better table on Wikipedia):
A B C I am the Lord your God pre 1 1 You shall have no other gods before me 1 1 1 You shall not make for yourself an idol 2 2 1 Do not take the name of the Lord in vain 3 3 2 Remember the Sabbath and keep it holy 4 4 3 Honor your father and mother 5 5 4 You shall not murder 6 6 5 You shall not commit adultery 7 7 6 You shall not steal 8 8 7 You shall not bear false witness against your neighbor 9 9 8 You shall not covet your neighbor's wife 10 10 9 You shall not covet anything that belongs to your neighbor 10 10 10
For fun, see if you know which is used by whom! The answer is below, mouse-over to see it:
A: Anglican, Reformed (pre = preface)
B: Orthodox; Jewish (Talmudic)
C: Catholic, Lutheran
As far as I know, almost all other denominations use A or B.
What are the reasonings for these different divisions? Especially since the first division didn't stick, I'm quite sure the differences can't be arbitrary.