Algebra with Stamps

I mailed out the bulk of the thank you notes for Daughter’s 2nd birthday party gifts. And wouldn’t you know it, it involved algebra!

I have so many stamps from the last 20 years, in every denomination you can imagine. I’m trying to use them up because I only save full sheets of stamps. (I’m a bit of a stamp collecting snob.)

Rule #1: No more than the required postage on any letter.

It has to be exact.

As of this writing, postage in the US is $.44 per letter.

I have $.33 stamps, $.37 stamps, $.41 stamps, etc. And I’ve purchased $.01, $.02, $.03, and on up to supplement and make my postage exact.

Rule #2: No more than 2 stamps of the same kind on a letter.

I like variety.

With these requirements, here are some of the combinations that I’ve come up with:

So how is this algebra?

Here is an algebra equation from the stamps in the picture:

10x + 17y = 44

The equation means x number of 10 cent stamps plus y number of 17 cent stamps will give me the exact total of 44 cents! So x=1 and y=2.

And here’s another:

10x + 24y = 44

The equation means x number of 10 cent stamps plus y number of 24 cent stamps will give me the exact total of 44 cents! So x=2 and y=1.

It would make it a better set of algebra problems if I allowed more than two types of stamps. But I’m sticking with my variety rule. 😀

How about it – will it make writing thank you notes with your kids more fun? More challenging? More annoying? Share your thoughts in the comments!

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