That’s Some Very Bad Mathematics

The Infamous “Double Decimal”

I am 40 years old, Canadian, and unhip, so my pop cultural references are many years out of date. As such, Dan Ackroyd is my guy on Saturday Night Live. His DVD best of was amazing. There is a skit named “Bad Ballet”, which features critics watching, well, some “very bad ballet”.

This sign is very bad mathematics. (To paraphrase a famous man, bad, very bad, tremendously bad, bigly* bad)

It is hard enough doing our jobs, without corporations pushing bad mathematics out into the world on their signs. Let’s say you are out with their children, and this happens:

Kid: what does that sign say?

Me: umm, one and ten and three.

Kid: one and ten and three what?

Me: dollars. No: One dollar, ten cents, and three.

Kid: three what?

Me: one dollar, and 103 thousandths of a dollar.

Kid: what?

You see, the decimal is quite comfortable where it lives, between the ones column and the tenths column. We are lucky to have beautiful, lovely, symmetrical place value- extending in columns of groups of 10 off into infinity in either direction.

We don’t need two decimals. Maybe, instead, gas companies could just sell it in dollars in cents, just like everything else? What, are they greedy or something?

The thing is, some kids WILL put in a second decimal, if their grasp of place value is shaky, and they thing the decimal “moves” all over. “Just move the decimal.” Umm, no. The decimal is the only thing in the world, perhaps, that moves less than my cat.

Until next time, this has been an episode of bad mathematics.

Have you seen any other #badmathematics? Tweet me some samples.

*I believe the proper term is “big league”, but truth is irrelevant in a post-truth world, so “bigly” it is. Bigly bad.