More Backwards Math

[Photo by *clairity*.]

Have you ever noticed how very different little girls are from little boys, in the way they play and in the way they think about things? Princess Kitten has been playing around with Backwards Math again, and my first thought was, “None of my boys would ever have done this with numbers.”

Identity Crisis

It seems that, in the land of Backwards Math, little numbers are born with only an equation. As they grow, they need to discover their value. And it is vital that they figure it out for themselves. Other numbers may offer guidance or advice, but they should never give the answer away.

Why is it so important for a little number to discover her value?

So she can get married, of course!

Kitten explained it to me: “Numbers can only marry another number that has the same answer. That’s how they know they will get along, because they have something in common.”

Our Story Unfolds

The following is a series of letters, exchanged between two numbers:
$-40 \div -20 = 2$ , and $-1 + -30 = -31$ .

Inverse Operations

I usually give Kitten a chance to edit any stories I write about her. As she read this over, she thought up something that she wanted to clarify:

A number like $-40 \div -20 = 2$ would only be able to get married to another division number or to someone with multiplication. And a number with addition, like $-1 + -30 = -31$ , could only marry one of its partners — a subtraction or another addition.

Hmmm. Can you tell we’ve been working on Order of Operations?

From the Kitten’s Mouth

While I was working on this post, Kitten wrote up the story for her own blog:

Negative Subtracting Problems

6 thoughts on “More Backwards Math”

Heh. So, what she’s saying is that addition and multiplication are different things.

I think Keith Devlin would be proud. 🙂

Good one, Eric! Thanks for the chuckle.

[Edited to add: Don’t worry if you missed the joke. You are probably not a math blogger — or else you’ve been on summer vacation the past few months. But if you’re curious, the backstory starts here and continues here.]

I found your blog last night and have really enjoyed browsing! My daughter is also in 3rd grade (as a homeschooler) but is working in a 5th grade math curriculum. She hasn’t worked much with negative numbers and I enjoyed reading about your daughters revelation!