Hundred
It's a landmark for a young child to count to 100; it sort of covers all the "ordinary" numbers. One hundred is obviously significant for other groupings: 100 cents is a dollar; 100 yards is a touchdown; 100 years is a century, and the landmark for a very long life. It makes sense, then, that in the Bible, 100 represents fullness or a state of completion, or in some instances simply "much." For instance, people marvel that Abraham had Isaac when he was 100 years old; the number represents the point at which the Lord, when growing up as Jesus, united the human elements of himself with the divine elements and in a sense became "complete.
James 2:21-23
21
Wasn't Abraham our father justified by works, in that he offered up Isaac his son on the altar?
22
You see that faith worked with his works, and by works faith was perfected;
23
and the Scripture was fulfilled which says, "Abraham believed God, and it was accounted to him as righteousness;" and he was called the friend of God.