Pam  00:00

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

Kim  00:07

And I'm Kim.

Pam  00:08

And this episode is a MathStratChat episode because we chat about our math strategies. Every Wednesday evening, I throw out a math problem on social media, and people from around the world chat about the strategies they use, and comment on each other's thinking. Which is the best part. 

Kim  00:22

It is the best part. And people love when you comment on their thinking. You know, when each other comment. That like gives you a little like puff of the chest and a high five. I love it. Okay, so this Wednesday, our math problem was 15 times 39. And we're curious, how would you solve this problem? Pause the podcast. Solve it first. The problem was 15 times 39.

Pam  00:42

Alright, Kim, I'll give you your head. What do you want to do? 

Kim  00:45

I'm going to go with 15 times 40.

Pam  00:48

Choices. You're going to look at this, and you're just like, "Choices, choices."

Kim  00:51

I know, I know. I'm going to go 15 times 40. 

Pam  00:53

Alright, you took mine, but I'll get another one. 

Kim  00:55

Sorry. That's 600.

Pam  00:57

Okay.

Kim  00:58

Which is really, I'm kind of thinking 39 times 15 because I want fourty 15s.

Pam  01:02

Yeah.

Kim  01:03

And then back up one 15, so I think that's 585.

Pam  01:07

So because you know 15 times 40 is 600. 

Kim  01:11

600, yeah.

Pam  01:11

Which you didn't say.

Kim  01:12

Oh! Oh, sorry. 15 times 40 is 600, but I have too many 15s, so I back up a 15. 

Pam  01:18

Okay. And so, (unclear). 

Kim  01:20

(unclear), Pam.

Pam  01:20

I did, actually. I said it out loud as you were going. Very nice. I'm going to guess that you know 15 times 4.

Kim  01:29

Yeah.

Pam  01:29

To know that 15 times 40. Do you know I did not used to know that? 

Kim  01:33

Really? 

Pam  01:34

Yeah. I do now. And I'm and I'm glad.

Kim  01:36

Is it because of clockwork? Like you know the clock fractions. (unclear).

Pam  01:41

You know, I just... I was the kid who memorized multiplication facts. And 15, I didn't memorize fifteens. So, it was...

Kim  01:48

Interesting. 

Pam  01:49

Yeah. There was no... I didn't play with fifteens. Not until I started this work.

Kim  01:53

I am so happy for you.

Pam  01:54

Me too! 

Kim  01:55

That you... Yeah.

Pam  01:57

Set me free. It's empowering. It's so empowering.

Kim  02:01

Well, and other people are really happy that you do too because a lot of work has been done over the years (unclear). 

Pam  02:05

We are spreading the word (unclear).

Kim  02:07

Yeah, yeah. Alright, what you got?

Pam  02:08

Okay, so I'm thinking about fifteen 39s as ten 39s. And then I'm going to find half of those to get five 39s. I think that's what I'm going to do this time. 

Kim  02:20

Yep. 

Pam  02:20

So, ten 39s is 390. Half of that is 150 plus 40 is 190. You might have just seen how I just did that. 

Kim  02:28

Mmhm.

Pam  02:29

And then 390 and 190 is like 400 and 180, which is 580. Whoa, I missed a 5 somewhere. If I'm going to be you, what did I do? 

Kim  02:38

What did you say? 

Pam  02:39

I don't know. 390. What's half of 390? Did I... Is that 195. Yes, that's where I screwed up.

Kim  02:47

Yeah. 

Pam  02:48

Half of 390 is 195, so it's 585. Yeah. There was something else that I wanted to...  

Kim  02:54

Wait, what did you say? 

Pam  02:56

Oh, you're killing me. 585. Yeah?

Kim  02:58

No.

Pam  02:58

No.

Kim  02:59

You said 10 of them was 390.

Pam  03:01

Yeah.

Kim  03:01

Are you writing anything down?

Pam  03:02

I am.

Kim  03:02

And then 5... Write it down. And 5... 

Pam  03:05

Write that down.

Kim  03:06

...is how much you say?

Pam  03:07

195.

Kim  03:08

Ah, I wrote down 145. It's me. It's not you. 

Pam  03:11

Okay. 4. 9. They kind of look the same. It's all good. I'm kind of... I don't know if this is going to work, but you taught me that mathematicians try things, and then they might just back out of them if they don't go well.

Kim  03:22

Oh, sure. Yeah. 

Pam  03:23

So, I'm super... Now, what was I going to do? Now, I've lost my train of thought. Come back, come back, come back. 

Kim  03:28

Oh, I wonder something. 

Pam  03:31

Well, I thought for a second about Doubling and Having, but that's dumb, right? Because then you would have 30 times 19.5. I mean, you could do that. 

Kim  03:41

Mmhm.

Pam  03:42

Twenty 30s, and then get rid of half of a 30.

Kim  03:46

I mean, listen, it's just kind of fun to play. I don't know that there's... 

Pam  03:49

Close to yours, right? If I do twenty 30s, that's like your fourty 15s. And then you subtracted one 15, and I would subtract half of 30. 

Kim  03:59

Mmhm. 

Pam  04:01

So, that's actually cool how it's connected. What were you playing with?

Kim  04:03

I just wrote down 15 times 39. And then I wrote 15 times 3 times 13. 

Pam  04:10

Oh.

Kim  04:11

And I was going to wonder if I know anything about 45 times 13, which I thought at first was pretty gross. But also I know that 45 times 3 is 135, so it's just 450 plus 

Pam and Kim  04:23

135.

Kim  04:24

Yeah.

Pam  04:24

Oh, that's not bad. 

Kim  04:25

I don't know that I like, you know, love that problem, but it's kind of fun to mess around with it. 

Pam  04:30

fifty 13s minus five 13s? No, I don't like that so much. Ha, nice. Okay, cool.

Kim  04:35

Alright.

Pam  04:35

That was fun. 

Kim  04:37

We can't wait to see what you all do every week. Join us on MathStratChat, and let us know how you think about the problem and comment on each other's strategies.

Pam  04:45

We post the problems on Wednesday around 7:00 pm Central time. When you answer, tag me and use the hashtag MathStratChat. Then join us to hear how we're thinking about the problem. Thanks for being part of the Math is Figure-Out-Able movement! Math is Figure-Out-Able!