Center for Mathematical Professional Learning and Educational Technology

Magic Bag

Magic Bag

Grade: 3-8

You’re cleaning out your closet and find a velvet bag in the corner. When you pick up the bag it feels heavy, and you find 24 pennies inside it. Before you go to sleep, you pull out the pennies and count them up again.

Now there are 27 pennies in the bag! When you check the bag at the end of the second day, you count 30 pennies.

At the end of Day 3, you count 33 pennies.

How many pennies will be in the bag after 10 days? 25 days? 100 days? Can you come up with a rule to find the number of pennies in the bag on any day?