"Odd" number would be kinda...odd, wouldn't it? Although 3 and 7 are "odd."
God often is very specific about His numbers in the Bible, isn't he? But we have to assume He rounded them off due to our finite mortal brains. Man is already sufficiently overwhelmed by His word at times. Imagine were "118.68" years to be His written Life Span? We'll have to axe Him when we see Him, "You Big Dawg, what wuz up whiff dose big-time odd numbers from da good book??"
Nah, I think it’s just easier to remember “Adam was 900” instead of “Adam lived 897 years and 10 months”.
It’s not the exact number that matters; I mean, if it was 897 instead of 900, would that crush your faith? If it turned out that really WAS 897 and 900 would your belief in the enternal truths and guidance in the Bible be diminished?
My guess for answers for both is “no”.
Just like the slaying of enemies of the Israelites (again, always a nice round number like 10,000) it’s about “that’s a really big number” that is easy to remember rather than the exact historical, empirical recording.