Math we can’t do

There are lots of humbling aspects of being a parent of a teenager. Among them, is the uneasy realization that they are getting smarter than you.

Proof of that comes to me daily in the SAT Question of the Day.

With my son starting to look at schools and getting ready for the ACT, I’ve been reading the question of the day for the SAT and the ACT the past few months.

Bottom line: 32 years after high school, I’m still pretty good at understanding what I read — and I still stink at math.

Here’s a recent SAT question of the day where I didn’t know where to start.

Read the following SAT test question and then click on a button to select your answer.

If S is the set of positive integers that are multiples of 7, and if T is the set of positive integers that are multiples of 13, how many integers are in the intersection of S and T?

(A) None

(B) One

(C) Seven

(D) Thirteen

(E) More than thirteen

I’m buoyed by the fact that only 40 percent of the 231,758 who tried this question got it right.

For all the agonizing we do about public education, I’m pretty sure the expectations and demands schools place on our children when it comes to math are harder than what I dealt with as a teen.

Bonus: Answer is E.

  • jon

    hardly even a math question so much as one of logic… if you have numbers going out to infinity then you are bound to have more then 13.

  • Jim

    Yeah – not to pick on you, Paul – but this is more of a quetion of math terminology recognition and logic.

    A rephrase might look like this:

    “If a group of numbers named “S” included only multiples of 7 and are greater than 0, and a group of numbers named “T” included only multiples of 13 and are greater than zero, how many numbers would S and T have in common?”

    If S and T include an infinite group of numbers, they must have infinite numbers in common – or, more than 13.

  • Phillip

    I went to a public school and got 6/7 right. I might swing the other way and say grammar is something not focused on, but I might be bitter about missing the sovereign question.

  • Kassie

    When I was a few years out of college, and more than 8 years past my last math class, I decided to go to graduate school. This meant taking the GRE and reteaching myself a lot of math, and learning some that I never learned in the first place, like geometry and trigonometry. It wasn’t fun and I forgot it all within a week of taking the test.

    Rarely do I need to do even basic arithmetic without the help of a calculator. I use my high school Spanish skills and geography knowledge more often than I use any of the math I learned in high school. In fact, I don’t think I use any math beyond what I learned in elementary school ever.

    I’m not saying math isn’t important. It is very important and students should be expected to learn advance math skills. But I’m not going to feel bad, or stupid, for not knowing how to answer an SAT math question. It just isn’t relevant in my daily life. My brain is too busy trying to remember my bank PIN and my co-workers’ names to keep track of these kind of things.

  • Joey

    It’s a good problem in that it tests problem solving skills, which are more important than arithmetic. If somebody asked you straight away, “How many numbers are multiples of both 7 and 13?”, you’d probably get it right away — every multiple of 7*13 works, and there are infinitely many of those. So what’s being tested here is the ability to turn a problem that looks complicated into one you can think about, and then take a few seconds to solve that one. I teach math at a university, and I can tell you I’d much rather have that sort of cognitive maturity in a student than the basic algebra skills these things usually measure.

  • Joey

    To clarify — because this seems to be a big mystery out there — we teach students math because it gives them problem solving skills. It’s sort of like, I do 15 pushups every morning, but not because I think pushups are an important life skill — it just gives me the strength and energy to do lots and lots of other things that are actually important.

  • Jim Shapiro

    Joey – Nice analogy. If it’s yours, I’ll bet you’re not getting paid enough.