Cross reference
Genesis 21:5
5 And Abraham `is' a son of a hundred years in Isaac his son being born to him,
Genesis 17:17
17 And Abraham falleth upon his face, and laugheth, and saith in his heart, `To the son of an hundred years is one born? or doth Sarah -- daughter of ninety years -- bear?'
Genesis 17:1
1 And Abram is a son of ninety and nine years, and Jehovah appeareth unto Abram, and saith unto him, `I `am' God Almighty, walk habitually before Me, and be thou perfect;
Romans 4:19
19 and not having been weak in the faith, he did not consider his own body, already become dead, (being about a hundred years old,) and the deadness of Sarah's womb,