I was given a receipt this morning at the coffee shop that had pink edges to it. Anyone who has ever worked a cash register knows that that could mean only one thing: you will be audited. Or, the paper is about to run out. I wasn’t very good at running a cash register.
Which reminded me of my high school math classes. A quite complicated mathematics word problem could be devised from the simple fact that the last few feet of a roll of cash register tape is marked with pink ink. It would go something like this:
“If a cash register tape roll is 180 feet long, and the last 10 feet are marked with pink ink, and each person who makes a purchase receives an average of 4 inches of tape as a receipt, and you make a purchase of a donut and a cup of coffee at the same time each day, and 356 receipts are given out each day from that register, how often will you receive a receipt marked with pink ink?”
When presented by a problem like this, I would always start with moral outrage. Why? Why am I subjected to such torture?
This is quickly replaced by logical outrage: when on earth would I ever be required to make such a calculation? But I was young, yet to enter the professional world, and I assumed that this was quite a common work assignment for most American workers. That, and figuring out where two trains would meet when leaving form opposite termini. (Aside: did you know that the main train station in Rome, Termini, is named so not because it is a railroad terminus, as I always thought, but because it is next to the Baths of Diocletian (Terme di Diocleziano). But that’s never on a math test, so never mind.)
Strangely enough, my assumption was correct. Not a day goes by that I’m not asked to make this or another similar calculation: how often will I pull a red ball out of bag full of white balls? (“What bag?” “The bag near the water cooler.” “I’ve never even seen that bag!” “This is going on your performance appraisal.”) How many contract employees will it take to do your job, assuming they are each 1.2 times as efficient as I am? (Answer: .002 contract employees.) Who died and made you king? (I can do this particular calculation in my head, but I choose not to share it.)
So, it’s a good thing I studied hard in high school, becoming proficient in many forms of mathematics. I attribute 90 percent of my professional success to my mastery of the concept of probability. That, and lying.