'Ninety nine' in the Bible

And when Abram was ninety-nine years old, LORD appeared to Abram, and said to him, I am God Almighty, walk before me, and be thou perfect.

And Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin.

What does it seem to you? If it happens a hundred sheep are with some man, and one of them went astray, after going (having left the ninety-nine on the mountains), does he not seek the one going astray?

And if he happens to find it, truly I say to you, that he rejoices over it more than over the ninety-nine that have not gone astray.

What man of you, having a hundred sheep, and having lost one of them, does not leave behind the ninety-nine in the wilderness, and go for that which was lost until he finds it?

I say to you, that thus there will be joy in heaven over one sinner who repents, than over ninety-nine righteous men who have no need of repentance.