Secret box

There is a box with 20 red balls, 10 green balls and 5 black balls. How many balls do we have to extract at least to get four balls with the same colour?

CLUE: Think about the worst possible situation.

Use comments to answer, writing your name.

(Translated from: 100 problemas de ingenio by Capó, M.)

The Girl Who Played with Fire

I'm reading the second book of the Millennium trilogy by Stieg Larson. The story starts with a paragraph about equations. Can you complete the gaps? Use comments and write your name:

PART 1: Irregular Equations

DECEMBER 16–20

Equations are classified by the highest (a)________ (value of the exponent) of their unknowns. If this is one, the equation is of (b)________  degree. If this is (c)________ , the (d)________  is of second degree, and so on. Equations of higher degree than one yield multiple possible values for their unknown quantities. These values are known as (e)________ .
The first-degree equation (the linear equation):

3x−9 = 0 (root: x = ______)

Constitución de 1812

Como sabréis hoy es el 200 aniversario de la aprobación de la primera constitución española, la constitución de las Cortes de Cádiz. ¿Sabias que en uno de sus artículos habla de las matemáticas?


Encuentra el articulo (incluido el número) e inclúyelo en los comentarios con tu nombre y curso.

Happy Pi Day. 3.14

Pi in the Sky

Botanical path in "Los Villares"

Did you like it? Comments are welcomed.
If you click on the path you will see some statistics. This was taken by a GPS sensor, though not a very accurate one. Can you find some information about GPS system? How does it works? Remember, produce your own information from what you read on the web, but do not copy-paste.


Ver "Los Villares" Botanical Path en un mapa más grande

We had a great time!!

The code

H+A+R+D+W+O+R+K = 98%

K+N+O+W+L+E+D+G+E = 96%

A+T+T+I+T+U+D+E = 100%

Can you find the code that has been used to find out these percentages?


Clue 1: Each letter has a value.
Clue 2: The order is important.
Clue 3: Do you know the alphabet?

Magic Squares

A magic square of order 3 is an arrangement of 3x3 = 3² = 9 numbers, usually distinct integers, in a square, such that the 3 numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square of order 3 contains the integers from 1 to 9.

Normal magic squares exist for all orders greater than 3, although order 1 magic square consists of a single cell containing the number 1. It's impossible to construct a magic square of order 2.

Iron plate with an order 6 magic square
 in Arabic numbers from China,
dating to theYuan Dynasty (1206-1368).

The constant sum in every row, column and diagonal is called the magic constant or magic sum, M.

Magic squares have fascinated humanity throughout the ages, and have been around for over 4,120 years. 

A magic square on the
Sagrada Familia church façade

There are magic squares in a lot of cultures, for example Egypt and India. They are on stone or metal and used as talismans, because people believed that magic squares had powers like longevity and prevention of diseases.

Source: Wikipedia

Now it's your turn:

Place integers from -4 to 4 in a magic square of order 3. Which number is the magic constant? How do you make your magic square? You have to do it in your notebook and show it to your teacher next wednesday january 11th.