…and to all who made me play with numbers along the way – thanks! Today’s NYTimes had an article, The Enemy of My Enemy, all about negative numbers. Gotta love a newspaper with a math opinion column! Anyway, it was with great pleasure that I read it, nodded over it and found a bit of pleasure in reading one of the first comments by a Tom of Edmonds WA:
The distributive property, a(b + c) = ab + ac, requires that a negative times a negative equals a positive:
-2 x 0 = 0
-2 x (3 + (-3)) = 0
-2(3) + (-2)(-3) = 0
-6 + ? = 0And it is clear that the product of -2 and -3 has to be 6, a postive number. We also had to assume that any number times zero equals zero.
Whoa. The pleasure: just that I could read the whole thing and understand it; a personal pleasure perhaps but still a good one. Often for these columns the comments are as enjoyable as the original article. Making the grey matter work on one cup of coffee: priceless.
Hey MaryBeth. Unless I’m missing something, I think the third equation is wrong. -2(3) x (-2)(-3) = 0 The answer should be -36. Type “-2(3) x (-2)(-3) =” into google and you’ll see.
Good eye -should be a plus sign!
This IS a fun article! So nice to see that there is a place for talking about and playing with math in the world beyond learning it in class. On another note, I’m supervised out of the Edmonds Library and live about 20 minutes from Edmonds WA…I wonder if “Tom” is someone who comes into the library?