A penny doesn’t buy much – maybe half a bite of a candy bar. So why do we bother carrying them around? Because most things at a store don’t cost an exact number of dollars; they might cost $2.18, or $5.99. And pennies are worth something if you save up giant piles of them. A man who saved pennies for 45 years ended up with thousands of dollars of them! Otha Anders decided he’d save every penny he found or got as change at the store. He finally brought them to the bank so he could pay his dentist, and they added up to $5,136.14! So Otha had his teeth cleaned, and had leftover money to buy a LOT of candy bars.
Wee ones: If you have 7 pennies in your pocket and you find 1 more, how many do you have now?
Little kids: If you find a penny starting on a Wednesday, and find another one every day until the last one on Monday, how many pennies do you find in total? Bonus: If you save the 2nd penny you find, then the 4th, then the 6th…what number penny is the 5th coin you save?
Big kids: How many pennies did Otha save if they were worth $5,136.14? Bonus: If Otha had saved 3 pennies a day for 45 years, would that have come to as much? (You can round off to estimate… there are 365 days in a year, but see if you can solve it without multiplying big messy numbers.)
Wee ones: 8 pennies.
Little kids: 6 pennies. Bonus: The 10th penny.
Big kids: 513,614 pennies! Bonus: It would not have been enough. With 365 days in a year, 3 pennies per day is about 1,000 for the year. So in 45 years he would have collected about 45,000 pennies or $450 — nowhere nearly enough. Even 30 per day wouldn’t have been enough!
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.