We've seen this a couple of times now.

What if I had a white marker, one that didn't show, but still held a place?

How will that affect things?

Image from Mr. Stadel.

# MathArguments180.com

180 Days of Ideas for Discussion in Math Class.

## Tuesday, April 15, 2014

### Day 88b: More combinations

Blue, green, yellow, and red ... We seem to be all set.

What if I get three black markers out of the drawer?

How will that affect things?

Image from Mr. Stadel.

What if I get three black markers out of the drawer?

How will that affect things?

Image from Mr. Stadel.

### Day 88a: Combinations!

Blue, green, yellow, and red ... We seem to be all set.

Now, what about the black, purple, and orange ones?

And BROWN!

Image from Mr. Stadel.

Now, what about the black, purple, and orange ones?

And BROWN!

Image from Mr. Stadel.

## Monday, April 14, 2014

### Day 87: n!

It's a straightforward question today. Calculators are allowed for this question because we here do not feel that six-digit multiplication is worth the effort. I mean, we know you COULD do it, but that's what a tool is for, right?

For any confused students, this problem is not suggesting that 851 is special! That's factorial notation,

For example, 6! = 6*5*4*3*2*1 = 720

For completeness, 0! = 1

Thanks to Darren, Right on the Left Coast, for this one.

For any confused students, this problem is not suggesting that 851 is special! That's factorial notation,

*n!,*meaning multiply the integer*n*by all the positive integers less than*n*. (Yeah,*n*must be a positive integer to begin with.)For example, 6! = 6*5*4*3*2*1 = 720

For completeness, 0! = 1

Thanks to Darren, Right on the Left Coast, for this one.

## Sunday, April 13, 2014

### Day 86b: Flower Petals

What fraction of this is yellow?

```
What fraction is yellow? How did you see it? pic.twitter.com/Y7OYAnkIgb
```

— Learning Maths (@LearningMaths) April 13, 2014

### Day 86: Circumcenter

*A rule from geometry says that three points determine a circle.*

Make a triangle with the three points. The perpendicular bisectors of the three sides will meet at the center of the circle. (Of course, you'll only need two but the third is confirmation.)

The points are A( 20, –18 ); B( 8, 18 ); C( –16, –6)

Graph paper, pencil and straightedge only.

## Saturday, April 12, 2014

### Day 85b: Related Rates

Describe how the two trucks must work together throughout this turn.

Can the rear truck get whipped?

```
Thinking... Thinking... #wcydwt RT @eeportal_com: Dispatching wind turbine blade to the site! Amazing!
```

— Geoff Krall (@emergentmath) March 28, 2014

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