How does this thing work to find curvature?

What kinds of information do you need to make the markings on that dial?

# MathArguments180.com

180 Days of Ideas for Discussion in Math Class. (as of 9July2014, we're in overtime!)

## Monday, October 20, 2014

## Sunday, October 19, 2014

### 285: Three Angles Revisited

Two days ago, I posted Okay for a Fifth-Grader?

Five Triangles said, "We posed the question slightly differently, our diagram providing an important hint to bring it to a more manageable level for younger problem solvers."

What do you suppose the "important hint" was?

Five Triangles said, "We posed the question slightly differently, our diagram providing an important hint to bring it to a more manageable level for younger problem solvers."

What do you suppose the "important hint" was?

## Saturday, October 18, 2014

### 284: Analyzing Digits

Why does this question not require a calculator?

When the integers from 1 to 30 are multiplied, determine how many consecutive digits starting from the ones (1s) position are zeros.

Would this be a fair question for some standardized test?

source.

## Friday, October 17, 2014

### 283: Ok for a Fifth-Grader?

Three squares of equal but unknown size.

Is this a fair question to ask a fifth-grader?

From a Numberphile video.

Is this a fair question to ask a fifth-grader?

From a Numberphile video.

## Thursday, October 16, 2014

### 282: Number puzzle

"The sum of two positive integers is 216. The greatest common factor of the two numbers is 24. What are all the possible pairs of numbers?"

What approach seems the easiest here?

I can see using solution methods such as:

- algebra
- guess and check
- organized list
- visual representation

Which of the two sentences eliminates the most numbers?

```
The sum of 2 pos int is 216 and their gcf is 24. Find all possibilities.
```

— David Marain (@dmarain) September 24, 2014

## Wednesday, October 15, 2014

## Tuesday, October 14, 2014

### 280: Rectangular Nets of Maximum Size - Connected

One possible arrangement. |

Find the net for the rectangular prism with the largest volume that you can make from a standard piece of paper (8.5" x 11"). Use whatever net arrangement of sides you prefer, but it has to be one connected net. (No loose pieces).

Find the sizes of the six rectangular pieces that form the rectangular prism with the largest volume that can be made from a standard piece of paper (8.5" x 11").

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