This is an easy project to make but pretty challenging to solve. You spin the blocks until you have solved the math problem on each of all 4 sides. Here is a short video showing how it works.

You will need to know 'order of operation' to solve the problems. If you don't recall, here it is:

**PEDMAS **

**P **- Parentheses first

**E** - Exponents (ie Powers and Square Roots, etc.)

**DM - ** Division and Multiplication(left-to-right)

**AS** - Addition and Subtraction (left-to-right)

__Another Way to Remember:__

** P**lease

__xcuse__

**E**__y__

**M**__ear__

**D**__unt__

**A****ally**

__S__Ok, enough of the school lesson. I made this puzzle easier by only including Multiplication, Division, Addition and Subtraction. You can obviously shorten or lengthen the puzzle to change the level of difficulty.

**I will give a free Instructables year long premium membership for the first person that can solve the math problem - post in comments. The numbers for the blocks, in random order, are shown in the Step 12. **

### Supplies:

## Step 1: Tools/Materials

__Tools:__

- Saw
- Drill or Drill Press
- Bits (3/16" and 1/2")
- Sander
- Ruler
- Pencil

__Materials:__

- 2x4 by 8" Long
- Paint
- Stencils (optional)
- Bungee Cord - 3/16" Diameter x 10" Long

## Step 2: Cut Blocks

I made the blocks from a scrap piece of 2x4. I started by cutting the width into 1.5" strips. I then cut each block to 1.5" long. I used a stop block on the miter saw to speed up the process.

## Step 3: Mark Center

Make lines between the corners to find the center.

## Step 4: Center Punch

I found it's a little easier to drill holes if you start with a center punch.

## Step 5: Drill Hole

Drill a 3/16" hole through each block for the 3/16" diameter bungee cord. Counterbore two of the pieces to capture the knots on the ends. After drilling, I sanded the blocks to break the sharp edges. I applied a light a coat of gray pickled stain to each block.

## Step 6: Number/Symbols

A stencil from a craft store was used to paint the numbers on the blocks. My better half helped with this tedious step.

## Step 7: Bungee Cord

This is a 10" long bungee cord with the ends (metal hooks) removed. I cut one end off the cord and slid both hooks off.

## Step 8: Feed Cord Through Blocks

Start with one of the counterbored ends and feed the clipped end through the block as shown. Keep feeding the blocks per your solution key until you have all the blocks on the cord.

## Step 9: Ends

The first end will have the clip from the bungee cord. Once you get to the last block, tie a knot to secure the bungee cord for the opposite end.

## Step 10: Pictures

The first picture gives you a reference on size and includes 3 of my other instructables.

## Step 11: More Pictures

No solutions shown :)

## Step 12: Can You Solve It?

The picture shows the puzzle in a random position. Side 1 through Side 4 are the four sides of the block. Since you don't have the puzzle in your hand, you will need to follow this order. If this doesn't make sense, refer to the pictures of the puzzle.

__Don't read the comments if you want to try to solve it yourself__

## Step 13: Excel Template

Attached is a MS Excel Template so you can generate new numbers. I also included an 11 block version. Enjoy.

## 12 Discussions

2 years ago

I solved by hand … put the "columns" on paper and cut out each column so I could maneuver easier.

2 years ago

8 - 2 x 3 / 2 = 5

3 x 3 / 9 + 6 = 7

4 / 1 + 6 - 4 = 6

5 + 4 - 2 x 4 = 1

Now I need to make a few !!!

Reply 2 years ago

We have a winner! I will send you a PM tonight. Question: Did you solve it by hand or use code?

2 years ago

I simply have to make a few of these. I will probably get carried away. I know I could make some using fewer blocks for little little kids and ones that have more blocks for some math teachers I know. Oh the possibilities. I have I can find should bungee cords.

Reply 2 years ago

Yes, fewer blocks make it easier. 7 block versions are pretty common. You should make an 11 or 13 block for the math teachers :). Another option is use words instead of numbers. As for bungee cords, you can buy them on Ebay or Amazon. I bought a 5 pack from Walmart for about $3.

Reply 2 years ago

I will use the bungees from the back of the car first. There are probably a few in the garage. My husband kept a lot of them. But finding them...

2 years ago

Liked how the stencil stage really caught my attention and you called it tedious

Reply 2 years ago

Yeah, I just don't have the patience for painting. However, it wasn't as hard as painting the dots on dominoes :).

2 years ago

I'm here from reddit.

So many solutions!

3/3+2+4=7

4/4-2+2=1

5-4+2+2=5

Reply 2 years ago

Nope. You must solve all 4 sides. The numbers also need to be in order.

Reply 2 years ago

Ohhh I missed that. I'll keep trying!

Reply 2 years ago

Yeah, it's pretty challenging to do by hand. Being lazy, I used excel to come up with the combinations.