## Cheaper pizza

The Daughter is doing order of operations at school.

I went to the local pizzeria on a recent Saturday night. The cost was \$10.50; I gave the cashier a \$20 bill and a \$1 bill. But he gave me back the dollar bill, and then gave me change for the \$20, which was \$9.50.

As it turned out, they were out of five-dollar bills, so he was going to give me nine one-dollar bills and 50 cents. Seeing this, the owner yelled, “Just charge him [me] ten bucks.” The clerk says, “But I’ve already closed the register.” The owner overrides the register to reopen it, puts back the \$9.50 and gives me a \$10 bill.

Of course, I gave the clerk \$21 in the first place so he would not have to give me a bunch of ones. If you’ve ever been in retail, you know that you don’t want to give away ones if you can help it, and certainly not nine of them. I knew that, the owner knew that, the clerk, not so much.
***
For some reason, I’m reminded by a story from long ago, where a guy I knew wanted to buy milk and a newspaper. At the time the milk was 99 cents and the newspaper, 35 cents. But the register wasn’t working properly, and couldn’t give the total, though it could give change. The problem is that the clerk couldn’t figure out the change from \$2, because he didn’t know the total of the purchase.

The guy tried to explain: “99 cents is a penny less than a dollar, so it’s \$1.34. These are non-taxable, so it’s \$2 minus \$1.34 is 66 cents.” This was too complicated.

I worry that when the computers all go down, no one will know how to add and subtract, never mind do multiplication and division.
***
I was watching the NBC Nightly News and saw this story: Gas Prices Drop to Lowest Level in Nearly Four Years, using the picture. I had to write to them.

“The average price drop is NOT 30% [as Brian Williams said], it’s 30 CENTS, as the graphic showed, from \$3.34 to \$3.04,” I noted. If it had been 30%, the drop would be about \$1.
***
The Daughter is doing the order of operations at school. At a website quaintly called Math is Fun, it reminded me that the order in which one does math problems is:
P
Parentheses first
E
Exponents (i.e. Powers and Square Roots, etc.)
MD
Multiplication and Division (left-to-right)
AS