"La mayor parte de las ideas fundamentales de la ciencia son esencialmente simples, y deben, como regla, ser expresadas en un lenguaje que cualquiera pueda comprender".
A. Einstein

lunes, 24 de noviembre de 2014


Chic@s, en esta tarde de lunes de poca luz y amenaza de lluvia igual os apetece jugar a un juego on-line sobre potencias de dos. Es muy friki, no os enganchéis.


Ya me contáis hasta qué número llegáis, yo no paso de 1024.




Primes and composites. Sieve of Erathostenes

This morning we studied what Primes and Composites are. Here you have the definitions.

The Sieve of Eratosthenes is an ancient method for finding all primes numbers up to a specified number.

It was created by Eratosthenes (275-194 B.C., Greece), an ancient Greek mathematician. Just as a sieve is a strainer for draining spaghetti,  Eratosthenes's sieve drains out composite numbers and leaves prime numbers behind. The numbers from 1 to 100 are listed in a table. We will  use The Sieve of Eratosthenes to find all primes up to the number 100 by following the directions below.

  1. Cross out 1 since it is not prime.
  2. Circle 2 because it is the smallest prime number. Cross out every multiple of 2.
  3. Circle the next open number, 3. Now cross out every multiple of 3.
  4. Circle the next open number, 5. Now cross out every multiple of 5.
  5. Circle the next open number, 7. Now cross out every multiple of 7.
  6. Continue this process until all numbers in the table have been circled or crossed out.
You have just circled all the prime numbers from 1 to 100!

Download presentation

Questions (to be answered as a comment):

1. How many prime numbers are there from 1 to 100?
2. List all prime numbers from 1 to 100.
3. Which number is the only even prime number?
4. An emirp (prime spelled backwards) is a prime that gives you a different prime when its digits are reversed. For example, 13 and 31 are emirps. List all emirps between 1 

Enjoy it.

miércoles, 19 de noviembre de 2014

Number gossip

Hi kids,

If you click on the image, you can go to the website that allows you to gossip on numbers stuff...

Have fun.

martes, 18 de noviembre de 2014

Unit 3: Divisibility

Hi kids,

Here you have the documents for UNIT 3:

Class notes for UNIT 3: Unit 3: Divisibility
Vocabulary for UNIT 3: Vocabulary

Si necesitas ayuda, siempre te quedará el tema en español de ANAYA.

Take care

martes, 11 de noviembre de 2014

Finding square root of numbers

Hi kids,

some of you asked me about how to calculate the square root of a number using an algorithm. Here you have a video, I hope that you find it interesting:

Take care

miércoles, 5 de noviembre de 2014

Square numbers

In mathematics, a square number or a perfect square is called an integer that is the square of an integer; in other words, it is the product of some integer with itself.

For example: 9 is a square number, since ita can be written as 3 × 3

These are always non-negative.

Here you have a picture showing some square numbers in a graph:

You can also practice with GeoGebra by clicking here.
And have a look at some interesting properties here.

Take care,