When grown-ups say they’re “burning money,” they don’t really mean that. They usually mean they’re spending too much money too fast. But it turns out money does get set on fire for real sometimes, and it’s not against the law! Dollar bills, $5 bills, $10s, $20s…they all get rumpled and dirty after they’ve been passed around a lot, even though they’re pretty tough (they’re made of cotton and linen). So they have to be pulled back out of “circulation” and replaced by new bills. That’s why our Bureau of Engraving and Printing has to print almost 40 million pieces of paper money every day, totaling about $750 million worth of money! Meanwhile, the old beat-up money does one more great thing: the city of Philadelphia burns it to make energy. Now, instead of just filling up a dump, the money is being recycled to run light bulbs and computers. That’s when setting money on fire is a good thing.
Wee ones: Which is worth more, a $1 bill or a $5 bill?
Little kids: If you have a $10 bill, a $5 and a $1, how much money do you have? Bonus: How many more bills would you have to get to have exactly $20 total?
Big kids: If burning a stack of 1,000 $1 bills makes energy to run 4 light bulbs, how many bulbs can you light by burning 4,000 bills? Bonus: If the Bureau prints 200 bills one morning and half are $20s while half are $10s, what’s the value of all that money?
The sky’s the limit: If one day Philadelphia burns $16,000,000 of money to make energy, and the pile has equal numbers of $1 bills, $5 bills, and $10 bills, how many of each were recycled?
Wee ones: The $5 bill.
Little kids: $16 in total. Bonus: 4 more $1s.
Big kids: 16 light bulbs. Bonus: $3,000, since the 100 $20s are worth $2,000 and the 100 $10s are worth $1,000.
The sky’s the limit: 1 million of each. Each “set” of a $1, a $5 and a $10 is worth $16, so there are 1 million of those sets.
And thank you Isabel L. for this great math topic!