## 2 Feb 2018

### New site!

This blog will no longer be updated. A new site is online at https://sites.google.com/view/mathschallenges/home.

## 25 Jan 2018

### Dingdong

Algebraic surface of degree $3$ generated by the algebraic equation $x^2+y^2+z^3=z^2$.

## 19 Jan 2018

### Challenge 26

Write $2018$ with the digit $5$ with the operations addition, subtraction, multiplication, division, power of $2$, power of $3$, square root, cubic root and factorial. Parenthesis are allowed. You can use numbers with more than one digit, like $55$, $555$ and so on.

Coming soon

## 9 Jan 2018

### Möbius Band by Keizo Ushio

Möbius Band $(1990)$ is a sculpture by Japanese sculptor Keizo Ushio $(1951)$, located at Mihama, Japan.

## 2 Jan 2018

### Daisy

Algebraic surface of degree $6$ generated by the algebraic equation $\left(x^2-y^3\right)^2=\left(z^2-y^2\right)^3$.

## 25 Dec 2017

### Challenge 25

Write $2017$ with the digit $4$ with the operations addition, subtraction, multiplication, division, power of $2$, power of $3$, square root, cubic root and factorial. Parenthesis are allowed. You can use numbers with more than one digit, like $44$, $444$ and so on.

With $5$ digits:

$44^2 + \left[\left(4-\frac{4}{4}\right)^2\right]^2 = 2\,017$

Can you do it with less digits?

## 22 Dec 2017

### Ellipse: gardener's method

An ellipse is the locus of points so that sum of the distances to the foci is constant. With two pins in a paper that represents the foci (green points), a length of string (in red) and a pencil (black point), we can draw an ellipse, as show in the animated GIF above. With this method, gardeners can create an elliptical flower bed easily!