“See a penny, pick it up, and all day you’ll have good luck!” On May 23 America celebrates National Lucky Penny Day. A penny by itself can’t buy much: you might need 50, 70, or even 100 pennies to buy a candy bar. That’s why people happily put them in these penny-crushing machines that squash the penny and stamp a picture on it. And they pay an extra 25 cents to run the machine! The question is, will that penny still bring you good luck?

*Wee ones:* What shape is a real, unsquashed penny?

*Little kids:* If you find a penny each day — Sunday, Monday, and so on — how many do you find in 1 week? *Bonus:* If you put in the penny plus 25 cents to make a stamped penny, how much money do you spend in total?

*Big kids:* If you’ve been collecting lucky pennies, and just 1 more will bring you to 1 dollar (100 pennies), how many do you have? *Bonus:* If you have 85 cents, how many funny squashed pennies can you make if it costs the extra 25 cents to stamp one, and how much money will you have left over?

Answers:

*Wee ones:* A circle – and in 3D, it’s actually a very short, squat cylinder.

*Little kids:* 7 pennies. *Bonus:* 26 cents.

*Big kids:* 99 pennies. *Bonus:* 3 squashed pennies, which will cost 78 cents (25+25+25+1+1+1). You’ll have 7 cents left over.