## Tuesday, April 10, 2012

### Three Friday 13ths This year

As you probably already know there are three Friday 13ths this year and they are exactly 13 weeks apart. The second is this coming Friday. The last time this happened was in 1984, the year made famous by George Orwell's novel of that name. I remember reading it in the mid '60s and wondering where I would be in 1984. Little did I know I would be in my third year in Vermont. The next time there will be 3 Friday 13ths in one year will be 2040. What will we all be doing then? Here are some interesting facts about 13. The Costa Concordia started sinking on the last Friday 13!

13th is an ordinal number, like first, second, third, fourth, fifth etc. We don't often talk about a thirteenth of something in a fractional sense but we do use third, fourth, fifth etc as fraction words. Yet another quirk of our strange English language. Fraction words are the same as ordinal words after you get beyond second/half. I remember working with a 2nd grade teacher once to teach fractions. We taught the students that a third as a fraction was one of three equal parts among other things. When the children lined up for recess one of the students looked up at me and said, "I'm third in line but I'm one of 16 equal parts!", referring to the 16 students in her class.  We discussed the two meanings of the word 'third' but I was never sure she understood.

Numbers occur in our lives in lots of ways; cardinals (counting numbers), ordinals (sequence numbers)  and nominals (naming  numbers). Room numbers, house numbers, telephone numbers and just about any number used to identify something is a nominal number. If you can replace the number with a name then it is a nominal. There are also classifications such as shoe sizes, the Beaufort wind scale, the Richter scale and Mohs rock hardness scale as well as rates such as prices, and measures such as temperatures. Each numeral (the written grapheme) has a different meaning when used as a different type of number.

Next time you fill your car up with gas, or petrol, look at the pump to see how many different types of numbers there are. It will take your mind off the price of the gas or petrol.