## 23 September 2022

### 662. Mathematical: 5 minus 3 is not 4

 Easy Medium Hard Extreme

ADD 4 matchsticks to make the equation true.

The following rules apply:
- No number is greater than 9
- Negative numbers are not allowed
- You may not change the equal (=) sign

## 10 October 2021

### 661. Reduce from 4 to 3 square matchsticks

 Easy Medium Hard Extreme

The size of the layout shown above is exactly 4 square matchsticks. Make sure to understand that A + B is exactly 1 square matchstick.

MOVE 4 matchsticks to reduce the size of the shape to exactly 3 square matchsticks.

## 25 September 2021

### 660. Six to five equal triangles

 Easy Medium Hard Extreme

There are 6 equal triangles in the layout above. MOVE 2 matchsticks to form 5 equal triangles.

## 07 September 2021

### 659. Triangle 3X3: Remove 6 leaving 0 triangles

 Easy Medium Hard Extreme

TAKE AWAY 6 matchsticks so that there are no triangles left.

## 28 August 2021

### 658. Mathematical: 0 minus 3 is not 7

 Easy Medium Hard Extreme

ADD 3 matchsticks to make the equation true.

The following rules apply:
- No number is greater than 9
- Negative numbers are not allowed
- You may not change the equal (=) sign

## 03 August 2021

### 657. Change the 2:3:4 ratio to 2:2:5

 Easy Medium Hard Extreme

The above square is divided into 3 parts in the ratio 2:3:4. Change this ratio to 2:2:5 by moving only 1 matchstick.

## 29 July 2021

### 656. Three right angles

 Easy Medium Hard Extreme

Three matchsticks form 2 right angles as shown in Figure A above. By moving only 1 matchstick you can create 3 right angles as shown in Figure B. However, this is only one solution and there are 7 more where 3 right angles can be created. Can you find them all?

The rules are:
- Start each time with the layout as in Figure A.
- Move only 1 matchstick.
- You may not move the horizontal matchstick in Figure A.

## 27 July 2021

### 655. Four to six squares

 Easy Medium Hard Extreme

Move only 2 matchsticks to create 6 squares. The squares are allowed to differ in size.

However, squares must be linked and each matchstick must form the side of at least one square.

## 10 July 2021

### 654. Increase the inner triangles

 Easy Medium Hard Extreme

This puzzle is similar to but different from numbers 517 and 592.

In the figure above 9 matchsticks were placed on a triangular grid to form 7 inner triangles.

What is the maximum number of inner triangles you can create by rearranging the 9 matchsticks on the grid?

## 06 July 2021

### 653. The farmer and his 4 sons

 Easy Medium Hard Extreme

A farmer lives on the area marked "A" on his farm. He decides to divide the rest of the farm between his 4 sons with the SIZE and SHAPE of each of the 4 farms exactly the same.

Add as many matchsticks as you want to the layout to show how he has done this.

## 04 July 2021

### 652. Three square units extreme

 Easy Medium Hard Extreme

Credit: The Moscow puzzles (1972) Boris A. Kordemsky

The length of a matchstick is 1 unit, so in the layout above 12 matchsticks were used to create an area "W" of 3 square units. (see puzzle 121 and also how area W was calculated below)

There is another way to create 3 square units, but you may NOT MOVE the matchsticks which from line AC. Can you find it?

Take note of the calculations below as you might need some of the information in your solution.

The area W was calculated as:
= Total area ABC - area X - area Y - area Z
= 1/2(3 X 4) - 1 - 1 - 1
= 3 square units

Angle 𝛳 was calculated as:
= arcsine(AB/AC)
= arcsine(3/5)
= 36.869898 degrees

We must now proof that the area of the parallelogram is 3 square units.

To calculate the height:
sin𝛳 = height/1
height = sin(36.869898)
height = 0.6 unit

The area of the parallelogram is:
= base X height
= 5 X 0.6
= 3 square units

## 03 July 2021

### 651. Three square units

 Easy Medium Hard Extreme

The length of a matchstick is 1 unit. Use 12 matchsticks to create an area of 3 square units. To make your life easier, 8 of the 12 matches have already been placed in the correct positions.

## 19 June 2021

### 650. Three squares different in size

 Easy Medium Hard Extreme

There are 5 squares in the layout above, 4 small and 1 big.

Move 2 matchsticks to create 3 squares of 3 different sizes.

## 16 June 2021

### 649. Three-way bridge

 Easy Medium Hard Extreme

There are three islands in the ocean and your challenge is to construct a bridge to connect them. Unfortunately, as can be seen with matchsticks A, B and C, the length of a matchstick is just too short to connect the islands directly.

How would you construct an interlocking bridge, that can actually carry some weight in real life, by only using matchsticks A, B and C? Also, the three matchsticks are not allowed to touch the ocean.

## 08 June 2021

### 648. Divide into 2 parts

 Easy Medium Hard Extreme

MOVE 2 matchsticks in the layout above to divide it into 2 parts equal in shape and size.

## 04 June 2021

### 647. Rugby

 Easy Medium Hard Extreme

A rugby player missed a kick to goal by kicking the ball to the right of the posts and also lower than the crossbar.

MOVE only 2 matchsticks to make the ball go through the posts and over the crossbar. You may not move the ball.

## 03 June 2021

### 646. Cross to squares

 Easy Medium Hard Extreme

There are no squares in the layout above. Move 4 matchsticks to change the cross into 4 EQUAL squares.

## 02 June 2021

### 645. Fix the equation

 Easy Medium Hard Extreme

You would need math skills to solve this one.

The equation 7/9 = 3 is not true. Move only 2 matchsticks to make it true.

## 01 June 2021

### 644. Polygon with 7 sides

 Easy Medium Hard Extreme

Shown above is an eight sided convex polygon built from 2 squares and 6 triangles. 17 matchsticks were used to achieve this. The outside angles are all greater than 180 degrees as illustrated with angle "a" above.

Create your own convex polygon. The following rules apply:

1. Polygon must have 7 sides
2. 12 matchsticks to be used
3. All outside angles to be greater than 180 degrees
4. There must be 3 equal sized triangles
5. There must be 2 equal sized squares
6. All matchsticks must be flat on the surface.

## 30 May 2021

### 643. Cup and saucer

 Easy Medium Hard Extreme

Move 4 matchsticks to convert the cup and saucer into 3 DIFFERENT in size triangles.

## 29 May 2021

### 642. Stacked triangles

 Easy Medium Hard Extreme

In the figure above are 4 equal triangles. Move 4 matchsticks to create 2 equal triangles.

## 28 May 2021

### 641. Three different squares

 Easy Medium Hard Extreme

MOVE 3 matchsticks to create only 3 squares. The 3 squares must have 3 DIFFERENT sizes.

Note that all matchsticks form part of a square i.e. there are no redundant matchsticks. There are also other solutions.

## 24 May 2021

### 640. Big and small squares

 Easy Medium Hard Extreme

There are 4 squares in the layout above. A broken matchstick is exactly half the length of a full length matchstick. Also, matchstick A is placed exactly in the middle of matchstick B.

Move 3 matchsticks to create 8 squares. All matchsticks don't have to be flat on the surface and square sizes may differ.

## 22 May 2021

### 639. From three to two squares

 Easy Medium Hard Extreme

Reduce the number of squares from 3 to 2 by moving 3 matchsticks. Squares may differ in size.