Lost Teeth and Compounded Interest

So "A" lost her 3rd tooth a few nights ago. She was so excited because she pulled it out all by herself. Well, the "Tooth Fairy" didn't remember about the tooth until about 4:30 in the morning! So, "she" quietly looked for the tooth for a good 10 minutes but could not find it! It wasn't until the next morning that the Tooth Fairy's husband said that he collected the tooth - no worries. When asked how much he left her, he replied, "35 cents". What?! 35 cents?! 35 cents won't even buy you a piece of gum nowadays!

So the Tooth Fairy had to tell her husband that for years now ;-) they have been giving the girls 25 cents for each tooth but that is added cumulatively - so the first tooth is 25 cents, the 2nd is 50 cents, the third is 75 cents, etc. The girls have figured out that pattern and were a little upset that the Tooth Fairy jipped them out of some money this time. Now they want to teach the Tooth Fair a lesson on interest compounded until the next tooth is lost ;-)