multiplying money

Fiora has been going running with me in the morning. I noticed she was only running a short distance and then walking because she got side aches. So one morning I asked her to run as many laps as she could in a row, and if she beat her "personal record" the next time we went by even one lap, she could have a prize in the vending machine. She ran one lap that day. She said she got another side ache. "OK, 1 lap is your PR, see if you can beat it next time."
However, the next time we ran she decided to see how long she could really go. We were outside instead of at the PG rec on the track, so I timed how long she ran at once and she did approximately 6 laps without stopping! So I told her on Monday when we went to the track she could have a prize. She asked if she does 7 laps on Monday can she have double prizes, and I agreed.
Monday came and we got up early to go to the track. I had forgotten about getting Fiora prizes and just grabbed 2 dollars that would pay our entry into the facility.  I don't know how I could have forgotten, I'm getting old and forgetful. But when we got there I realized I had forgotten to get two more dollars for Fiora's prize money, and said "Fiora! I am so sorry I forgot your prize money!" She said, "that's ok mom." But I felt bad. As we were walking into the rec center I pulled out the two dollars I had grabbed and said, "I really wanted to reward you for running so hard, I wish I could make these dollars multiply." As I said this I fanned the dollars in my fingers, and a third dollar magically appeared. "What?" I stared in disbelief. "Fiora a 3rd dollar appeared."  "What? mom did you do that on purpose?" Fiora asked.  "No, I promise, I didn't! I don't know how it got in my pocket." So I checked my pocket and magically another dollar appeared!  I pulled it out!  "Look Fi! There is another dollar in case you want to beat your personal record and get double prizes!"  "Wow!" Fiora laughed, and I laughed, and we thought it was a mini-miracle to keep Fiora working on her goal to be a runner and exercise.