# A rich problem

OK, I don’t do this often but I’m going to share my latest get rich quick scheme.  Everyone can do it and it’s perfectly legal.

I was inspired to share after watching this video yesterday.  It’s a lesson in Mathematics, Business, and Consumer Studies in itself.

It’s the 99 at the end that got me thinking.  The Canadian penny has been removed from circulation (or at least is in the process) and so prices have to be adjusted accordingly.  This information from the Canadian Mint explains the rounding rules for cash transactions.  The key is cash transactions.  If the transaction ends in .03, .04, .08, or .09, the transaction is rounded up to the next amount that is payable by the remaining currency.  (nickel, dime, quarter, dollar)  If the transaction ends in .01, .02, .06, .07, the final bill is reverted to the lower amount payable by the same currency.

Remember the signs on gas pumps when self-serve became popular “If you pump pennies, you pay pennies”.  Be careful if you’re paying cash.

My first inclination was to hoard until this appeared on Storage Wars.  “A Canadian penny?  That’s a hundred dollar bill all day long”.

If you’re not paying by cash and using debit or credit instead, the exact amount is paid.  So here was my plan.  I would come ready to pay both ways depending upon the final bill.  If it was going to be rounded up and I get charged the extra pennies, I would pay with debit or credit.  If I could make a penny or two by paying cash, I would pay cash.  Mental math was put on trial but you also have to wait for the taxes to be added so I just waited until the cashier gave me the final total.

It seemed to make sense and I tried it, lasting for like one or two days.  By then, it had become too much effort with not much benefit and I realized I could make more money collecting bottles from the ditch while walking the dog.

It really wasn’t original either.  A conversation at Tim Horton’s let me know that others had this plan too.  I wonder if they still are doing it.

Anyway, the wealth of the situation may not be a personal wealth but I think it would be a fun and relevant activity for a Computer Science program.  Write a program that obeys the rules and pays either by cash or debit/credit depending upon the total.  You’d just need some test data.

How about a class bringing in their grocery receipts for a week.  On second thought, it’s probably not a good idea as students would be bound to compare.  The worst would be to find out who buys Heinz ketchup and who buys French’s.  But, in reality when you think about it, it’s not the complete total that’s required.  Just the digits after the decimal.  That would be easily collected and put into an CSV text file.  Perhaps lastname, value.

Then, the program would run and determine the total paid if by cash or debit/credit and how much the savings/cost would be.  Total the value for the class.  What’s the net effect if everyone used cash or if everyone paid with debit/credit or if everyone paid with the best possible option?  It seemed like a fun idea so I whipped up my own in Small Basic.  I didn’t have a class of receipts so just generated some random numbers.  Not surprisingly, I ended up almost even in the process.  So much for getting rich quick.  As I was contemplating this, I realized that it would be a nice exercise in a spreadsheet not dissimilar to what Brandon Grasley did here.

I guess the bottom line is that sometimes the best problems are all around us.  We just have to think them through.  That’s far more interesting and relevant to Canadians since the demise of the penny.  If you’re an American reader, you might want to get prepared.  Word is that you’re thinking of following our lead.

## 3 Replies to “A rich problem”

1. Andrew Forgrave says:

Clearly, the frequency with which you can rake in these pennies is the key. A keen student would be wise to maximize their return by identifying the least expensive and most useful item (candy?) that they could spend the whole day purchasing in order to quickly generate substantial numbers of saved pennies.

Of course, access to an unlimited supply of capital which one could spend non-stop throughout the day in these carefully planned transactions would generate the greatest return on investment in both cash and time.

Continuing in this vein, the doubly- wise student could double dip by turning around and reselling their purchase at a price which would allow them to round up and generate a couple of extra pennies on each sale to boot!

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2. Now there’s a plan that definitely needs a visual organizer to follow!

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