In today’s MathStratChat, Pam and Kim discuss the MathStratChat problem shared on social media on December 21, 2022.

Note: It’s more fun if you try to solve the problem, share it on social media, comment on others strategies, before you listen to Pam and Kim’s strategies.

Check out #MathStratChat on your favorite social media site and join in the conversation.

Pam:

Hey, fellow mathematicians! Welcome to the podcast where Math is Figure-Out-Able! I'm Pam Harris.

Kim:

And I'm Kim Montague.

Pam:

And this episode is a MathStratChat Episode. What is MathStratChat? Well, every Wednesday evening, I throw out a math problem on Twitter, Facebook, Instagram, all the social media. People from around the world chat about the strategies they use. It is super cool to see everyone's thinking.

Kim:

Okay, so this Wednesday, our math problem was 63 minus 49. How would you solve this problem? Pause the podcast, solve it any way you want. The problem was 63 minus 49, solve it, and then come back to hear how we solved it.

Pam:

Alright, Kim, I want to hear how you solved this one first.

Kim:

Okay. Well, you know you could probably predict what I'm going to say.

Pam:

Ooh, should I predict?

Kim:

You could. Yeah, I think (unclear).

Pam:

(unclear) did not talk about. Yeah, we didn't talk about this. I predict that you used an Over strategy.

Kim:

Yes!

Pam:

Because you taught me that. Huh. Interesting. Nice.

Kim:

I love the Over strategy. So, I... You know, not that this Thanks. matters in any way. But because of that 49. And I really didn't

Pam:

Not what I did. write much down. I just wrote down 63 minus 50. I didn't write that down. I just wrote down 13. It would be 13, if it was 63 minus 50. But I subtracted too much. I only need to subtract

Kim:

What did you do? No? Okay. 49. And so, then, I added 1 back on. So, instead of 13. It's 14.

Pam:

Yeah, so maybe partly because I wrote this problem, I had a strategy in mind. And so, I'm... It's funny, because I wrote it a long time ago, and when I looked at it again today, I was like, "Oh, yeah, I see nine 7s in 63."

Kim:

Yeah.

Pam:

So, when I see 63, 9 times 7 sort of is a thing that I can think about. Minus 49 is seven 7s. So, nine 7s minus seven 7s is two 7s. And two 7s is 14.

Kim:

Nice.

Pam:

Bam!

Kim:

I do like that. I have seen that strategy before in maybe another problem that you've created or maybe you've talked about it before. I like it.

Pam:

Yeah, super cool. I was at a numeracy workshop once, and we were doing... I think it was addition actually. And I was asking people how they were thinking about solving the problem. And one of the participants said, "Oh, yeah, I just... These numbers just pop." And factors popped out. I had never thought about that before. And I was like, "Say more about that." And so, since then, I've tried to write problems where I can kind of train my brain to recognize those factors. You might find it interesting that when you said, "Okay, now it's your turn to solve it." I actually wrote down 7 times 9. And I thought, "Okay, so seven 9s." And then, I looked at the 49, And I wrote seven 7s. And I was like, "Oh!" And then, I switched it and wrote 9 times 7. So, you kind of have to play with the relationships. I knew there was something in common, but I had to play a little bit to determine that it was 7s I was thinking about, not 9s. Yeah.

Kim:

And it's really helpful the way that you said it.

Pam:

Nine 7s.

Kim:

Nine 7s

Pam:

Seven 7s.

Kim:

Seven 7s, mmhmm

Pam:

To be left with two 7s. Yeah.

Kim:

Mmhmm.

Pam:

Kind of a cool strategy.

Kim:

Well, well done. I like it. Alright, we can't wait to see your math strategies. I wonder if it's like one of ours or something entirely different. Represent your thinking, take a picture of your work or screenshot that on your phone, and tell the world on social media. While you're there, check out what other people did and comment on their thinking.

Pam:

Yeah, and tag me on Twitter: @PWHarris. Or

Instagram:

pamharris_math. On Facebook: Pam Harris, author, mathematics education. And don't forget to use the hashtag MathStratChat, and make sure that you check out the next MathStratChat problem that will post on Wednesdays at 7:00 p.m., Central Time. And then, pop back here to hear how we're thinking about the problem. We love having you as part of the Math is Figure-Out-Able movement! Let's keep spreading the word that Math is Figure-Out-Able!