4/13/2017

Week 34: Pipes and Estimations

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Welcome to Table Talk Math. This week, I'm sharing a fun and scary image, then asking you to estimate.

Table Talk Newsletter #34

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How many pipes are stacked on the bed of the truck?

How did you count?

On our way to baseball practice last week, my family and I were approaching the back of a shipping truck carrying a whole bunch of steel pipes. From the back, my 6 year-old belted out, "wow, that's a lot of pipes!"

It sure was! Where were they heading? What could they be used for? How much is all that steel worth? While those questions ran through my mind, two others were more accessible: how many do you see, and how did you count?

My youngest, 4 years young, went with his upper bound: "A ZILLION!"

My oldest, the 6 year-old, started counting. Well, I wasn't about to sit behind this truck for two hours, so I had him count as much as he could and then guess. He has not yet learned multiplication, so his counting to 27 and guess of 500 was just that: a guess.

Meanwhile, my wife and I took a swing at the number. Here's what I did:

In the bottom left, there is a group.
In that group, there are 14 pipes across and they are stacked 9 pipes tall (from what I counted).
Knowing that, 14 * 9 can be broken down to 10 * 9 and 4 * 9.
10 * 9 is 90.
4 * 9 is 36.
Adding them together, there are 126 pipes in each set.
There are 2 stacks of 4 sets, so 8 total sets.
126 * 8 is 1008.
There are 1008 pipes on that truck.

My wife came up with a different way of doing it:

I counted all the way across and got 27 pipes.
I counted all the way up and got 36 pipes.
Hang on... (gets calculator)
There are 972 pipes.

So, which one of us is right? Neither? How did you do it?

Share your method and solution with me and I will feature it on the website! Here are a couple so far.

@Jstevens009 8 sections of about 15 by 10. So 150 times 8. Or 300 times 4. Or 600 times 2. 1200 pipes.
— Martin Joyce (@martinsean) March 31, 2017

@Jstevens009 Hmm, looks like 9×15×8 = 1080. But I cheated by counting!
— Josh Fitzgerald (@bamkzer0) March 31, 2017

If you have any questions, please feel free to contact me on Twitter (@TableTalkMath) or comment below. Be sure to have your friends sign up for the newsletter at tabletalkmath.com for weekly updates.

Thank you for taking the time to improve math fluency for children, one table talk conversation at a time.