lunes, 4 de agosto de 2008
Maths Is Fun
Explore primary and intermediate math, solve puzzles, and play games.
Enter in the Numbers section. You can work with numbers, its basic operations, fractions, decimals, percentages...
Try the Algebra section. It's very interesting and complete.
* Basic Operations and its order.
* Linear Equations
* Quadratic Equations
and much more.
Also there are puzzles, games...
miércoles, 5 de marzo de 2008
domingo, 11 de noviembre de 2007
You can round off a number in different ways: Example:
to the nearest unit: 643,78 = 644,
to the nearest 10 (ten) --> 643,78 = 640
to the nearest 100 (hundred) --> 643,78 = 600
to the nearest 1/10 (tenth) --> 643,78 = 643,8
More interactive exercises:
(a) All corresponding angles are equal. Angle1 = Angle5
(b) Each pair of alternate angles are equal (congruent). Angle1 = Angle3
(b) the interior angles on the same side of the transversal are supplementary. Supplementary angles are any two angles whose sum is 180 degrees. Angle1 + Angle2 = 180º
Exercise: r line is parallel to s line. The angle1 measures 60 degrees.
Find the measures of the other seven angles in the figure (right).
Clic on the picture below to see a graphic proof.
Angle2 = 120 degrees since it is supplementary to angle 1.
Angle3 = 60 degrees since Angle1 and Angle3 are vertical angles.
Vertical angles are two nonadjacent angles (opposite angles) formed by two intersecting lines.
Angle4 = 120 degrees since it is supplementary to angle1.
Angle5 = angle1 = 60º, by the Transversal Postulate.
Angle6 = angle2 = 120º,
angle7 = angle3 = 60º, and
angle8 = angle4 = 120º, by the Transversal Postulate.
Vocabulary: (to) intersect = intersectar, cortar
postulate= postulado, enunciado intuitivo que no se demuestra.
(to) measure= medir
sábado, 10 de noviembre de 2007
Do you like impressing them?
Use this easy number trick.
1º- Tell someone of them to pick a two digit number.
2º- Then tell them to add the digits, and subtract this sum from the original number.
3º- Then tell them to add the digits of the result.
Now, you will guess this result.
Read the comment below (Comentarios) to know it
domingo, 28 de octubre de 2007
Is 2064 divisible by 6?
Is 5 a factor of 75?
Is 17 a prime or composed number?
Write all factors of number 24.
Exercises on divisibility (2º ESO)
More exercises on divisibility (1º ESO)
More exercises on divisibility
A video about primes, factorization, divisibility...
Every straight line segment has three points with three numbers.
The sum of the three numbers in each segment is equal to a same number.
So, in a five-pointed magic star you can see numbers from 0 to 14 and the the sum of three numbers in each segment always is 21.
Exercises on five-pointed magic star
In a seven-pointed magic star you can see numbers from 0 to 20 and the the sum of three numbers in each segment always is 30.
Exercises on seven-pointed magic star
These exercises are very good for increase your mental calculations.
viernes, 26 de octubre de 2007
a) 16sometextb) 18sometextc) 20sometextd) 22 sometext Answer: 3 · 9 - 4 · 2 + 6 - 5
For more fractions problems, see the following pages (tutorials online with oral english explanations):
Prime factorization, GCF (Greatest Common Factor), LCM (Least Common Multiple), Decimals and fractions
Adding and substracting fractions.
Adding and substracting fractions and mixed numbers.
Fraction operations: multiplyimg fractions and mixed numbers.
Taken from ClassZone.com
domingo, 21 de octubre de 2007
1- There can be 39 students in the Computer class. The class has 14 boys and 17 girls. How many more students can join the class?
2- A pair of shoes cost $10 and a pair of sandals cost $8. What is the total cost of 3 pair of shoes and 4 pair of sandals?
When Andrew crosses the finish line, Charles has run only 95 metres.
So Andrew wins the competition with a lead of 5 metres.
During a second competition, Andrew (who wants to make the competition more “balanced”) , penalizes himself voluntarily , starting 5 metres back the starting-line.
It is supposed that the two athletes run with the same speed they had during the first competition.
Who will win the second competition?