## Tuesday, November 24, 2015

### Topologist's Map of the United States

To a topologist, two shapes are "the same" if one can be stretched, twisted, and distorted into the other shape without breaking or tearing it.  Shape, angle, size, distance, and position can be completely different, and yet the two shapes are topologically equivalent.

This is a topologist's map of the 48 contiguous United States.  While the states are not recognizable, you can work out which is which by how the states are connected to each other.  For example, which is the only state that borders exactly one state?  Can you find it on the topologist's map?  Can you identify all the states?  (One note:  Lake Michigan is included as one of the polygons, and the state of Michigan is represented as a single polygon, which was necessary to avoid some strange results.  So all together there are 49 polygons here.)

For the solution, click "Read More" below.

## Wednesday, November 11, 2015

### Geometric Progressions

For the solution, click "Read More" below.

## Wednesday, October 28, 2015

### Four Paths Problem

For the solution, click "Read More" below.

## Tuesday, October 20, 2015

### Coincidence? Why are Primes Clustered Around Multiples of 6?

For the solution, click "Read More" below.

## Wednesday, October 7, 2015

### The Colored Blocks Problem

For the solution, click "Read More" below.

## Thursday, October 1, 2015

### Which Net?

For the solution, click "Read More" below.

## Monday, September 14, 2015

### Flower Problem

For the solution, click "Read More" below.

## Thursday, September 3, 2015

### Colored Blocks Problem #2

For the solution, click "Read More" below.

## Saturday, August 22, 2015

### Folded Polyhedra

For the solution, click "Read More" below.

## Thursday, August 13, 2015

### The Box Problem

For the solution, click "Read More" below.

## Wednesday, August 5, 2015

### Common Factor Puzzles

For the solution, click "Read More" below.

## Saturday, August 1, 2015

### Floating Blocks Problem

For the solution, click "Read More" below.

## Friday, July 24, 2015

### Four Cards Problem

For the solution, click "Read More" below.

## Monday, May 11, 2015

### Flattened Polyhedra

For the solution, click "read more" below:

## Tuesday, May 5, 2015

### Handshake Problem

For the solution, click "read more" below:

## Tuesday, April 28, 2015

### Three Boxes Problem

For the solution, click "read more" below:

## Friday, April 17, 2015

### Strange Symbols

#### Solution to puzzle 1:

Solution to puzzle 2:

## Monday, February 2, 2015

### Stacked Dice

Solution: The sum of any two opposite faces of a die is 7.  So, excluding the top face, the sum of the numbers on the 3-dice tower is always equal to 7 x 2 x 3 = 42, and it doesn't matter how we arrange the dice.  The only thing that affects the total sum is the number showing on the top, which can be any number from 1 to 6.  So the minimum sum is 42 + 1 = 43 and the maximum sum is 42 + 6 = 48.  For 20 dice, the minimum sum is 7 x 2 x 20 + 1 = 281 and the the maximum sum is 7 x 2 x 20 + 6 = 286.  For n dice, the minimum sum is 7 x 2 x n + 1 and the maximum sum is 7 x 2 x n + 6.

## Tuesday, January 20, 2015

### Spilled Juice Problem

#### The Spilled Juice Problem

Henry had just finished his math homework when he spilled orange juice all over it.  Can you help Henry figure out what his homework problems (and solutions!) were?

## Tuesday, January 13, 2015

### Six Toothpick Problem

For the solution, click "Read More" below.

## Wednesday, January 7, 2015

### The Two Mangoes Problem

#### Solution:

(1)  If one mango and one banana cost \$4.70, then two bananas and two mangoes cost twice as much:  \$9.40.
(2)  From there we can use the middle bag to find the cost of a single banana:  \$13.00 (2 mangoes and 5 bananas) - \$9.40 (2 mangoes and 2 bananas) = \$3.60 (3 bananas).   If 3 bananas cost \$3.60, then each banana costs \$1.20.
(3)  From the first bag then we can see that a single mango costs \$3.50 (\$4.70-\$1.20), and so the bag of 2 mangoes costs \$7.00.

### PLAYFUL MATH BLOG CARNIVAL #163

BLOG CARNIVAL #163....LET'S GO! Fun fact: The number 163 is prime, which we can prove simply by showing that it is not divisible by 2, 3...