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

## 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!

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