In today’s MathStratChat, Pam and Kim discuss the MathStratChat problem shared on social media on October 25, 2023.
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.
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Hey, fellow mathematicians! Welcome to the podcast where Math is Figure-Out-Able. I'm Pam Harris.
And I'm Kim Montague.
And you're listening to a MathStratChat episode, where every Wednesday evening, I throw out a math problem on social media, and people from around the world chat about the strategies they use. It's super to see everyone's thinking.
Alright, ya'll, this Wednesday, our math problem was 13 times 75. We're wondering how would you solve this problem? Pause the podcast, solve it any way you want. It is 13 times 75. Go ahead and solve it, and then come back to hear how we're going to solve it.
Can I just say that I have a really hard time that we do this now because I want to see the problem when you post it, and I try really hard not to, so that I'm fresh looking at the problem. And so later, I can see what people did, but oh it's so hard.
Too bad. So sad. Alright. Well, should we flip a coin? Who's going first today? Call it. Call it.
I'll go first.
I'll just go. Okay.
So, 13 times 75. Not going to go percentages because I don't really love 75% of 13. But I am going to say I know 10 times 75, which is 750. And strangely, I know 3 times 75 is 225.
No way. Do you really know that?
Yeah, I don't have any idea why. For some reason in my brain, I picture three $0.75s, and I just know it's 225. I don't have any idea why. There must be something that I've like purchased 100 times, 3 of them for $0.75, but I cannot for the life of me figure out what it would be.
So, together I got 975.
You add those together, it's 975. That makes sense. Cool. You know, I am going to go percents today.
So there. Yeah. So, I'm thinking about 75% of 13 as 75% of 12.
75% of 12. I'm thinking about chunking 12 into four 3s. So, I need 3 of them, so that's 9. And then, I need 75% of 1, which is 75, or 0.75.
And so, I've got 9 plus 0.75, which is 9.75. But then, since it was percentages, I need to scale that up 100, so I get 975. Yeah. Hey, but another way that I was kind of messing around was that last week, we had... Let me just remember. No, a few weeks ago. A few weeks ago, we had 12 times 75, that was 900.
And then, we had 14 times 75, and we got 1,050.
And so, 13 times 75 is right in the middle of 12 times 75 and 14 times 75 and 900 and 1,050 are 150 apart.
So, to go right in the middle, I would need to divide that by 250 divided by 275. And so, 900 plus 75 is 975. Another way of thinking about it.
Both Pam and Kim 03:10
Very cool. 75s are fun.
Lots of fun.
Alright, ya'll, share with us your strategy, and we're super excited to see it. Would you represent your thinking. Take a picture of your work! We want to see your actual sketched out representation! And tell the world on social media. And while you're there, please comment on what other people did. It's super fun to see a whole string of people saying, "Me too! That's what I did. I thought that way too!" And go ahead and comment.
And you have to say, those of you who've had someone comment on your thinking, how fun that is, right?
Yeah, for sure.
Like, when someone else says, "Oh, brilliant strategy!" You're like, "Oh, I had a brilliant strategy!" Like, there's something about giving people that "Attagirl! Attaboy!"
Yeah, Cooper loves it.
He is so excited.
Absolutely. Hey, and while you're there, tag me at @PWHarris. Or Instagram, PamHarris_math. Or Facebook, Pam Harris, author mathematics education. And use the hashtag MathStratChat. And then, check out our next MathStratChat problem we'll post about 7pm on Wednesdays, and then come back here and listen to Kim and me talk about how we solve 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!