21 Jun 2011

fractions!

Fraction is part of a whole. The following illustrate the concept;The figure has 4 parts and only 1 part of the figure is shaded.

fractions-image

fractions-image

Now, suppose you go to Domino's pizza, you may order a medium pizza. If your pizza has 8 slices and you did not eat the whole pizza, this means that you only ate parts of the whole pizza.

Let's say you don't have a big appetite and eat only 2 out of those 8 slices. The following figure illustrate the situation

Pizza-image

we write 2/8 and we call 2 the numerator and we call 8 the denominator.

fractions-image

Notice that a (/) can also be used to separate the numerator with the denominator.

The expression 2/8 can also mean 2 divided by 8. If you use a calculator, the answer will be 0.25 and 0.25 is a decimal. Don't worry about this now. I will teach you decimals in a different unit.

Common sense also tells us that if we eat 2 slices and there are 8 slices, well, we ate only one-fourth of the pizza.

How can we write one-fourth with a numerator and a denominator? May be you know already! If you don't, try the following:

You make 4 piles with your slices with each pile having 2 slices.

fractions-image

Eating 2 slices out 8 is the same as eating 1 pile out of those 4 piles. We can then write 1/4, which is also equal to 0.25 or 2/8

There is something interesting about 1/4 and 2/8.Although they both have different numerators and denominators, they are both equal.

We call 1/4 and 2/8 equivalent fractions.

Other examples are:

1/2 and 5/10

1/3 and 4/12

2/5 and 4/10

Notice that to get from 1/4 to 2/8, all we need to do is to multiply both numerator and denominator by the same number that is 2.

In the same way, to get from 1/2 to 5/10, we can multiply both numerator and denominator by 5.

2/8 and 5/10 are called higher terms. Be careful! It is not because 2/8 is bigger than 1/4 and 5/10 is bigger than 1/2.

Compared to 1/2, 5/10 is a higher term only because it has a bigger numerator and a bigger denominator. However, we saw before that 1/2= 5/10 = 0.5

Notice too that you can go from a higher term to a lower term. For instance, to bring 5/10 to a lower term, all you need to do is to divide both numerator and denominator by 5. You will get 1/2

Going from higher terms to lower terms means that you are simplifying. To get the simplest form, divide the numerator and the denominator by the largest number that divides into both evenly.

For instance, to bring 10/40 to its simplest from, divide both 10 and 40 by 10. You will get 1/4.

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