Possible Duplicate:
Rationalist Position on Bible Ancients' Long Lives
The bible states that Abraham has lived for 175 years, Yishmael lived for 137 years, and so on and so forth.
Now, either they really lived that long (which given that 100 years ago people rarely lasted past 60, doesn't sound very likely), or they counted years differently.
Anyone knows how did they count years, and subsequently, how long did Abraham really did live?