Counting with Kate

Today I was going over Kate's homework and noticed that she had counted by 10's correctly except for one spot...10, 20, 30, 40, 50, 60 70, 80, 91, 100. I was so confused...I have heard her count by 10's to 100 soooo many times. I mumbled it under to my breath to myself...80, 91, 100...and then I heard it... 91-100 she elongated the "one" in 100 and says 91-100. I asked her to count by 10's and listened carefully...Yep...just as I thought...seventy, eighty, ninety-one, hundred. . I got out the 100's chart, showed her the mistake and she laughed and said, "Well that makes a lot of sense!" Sure does, baby girl. Sure does.