Chris Mohan Maths



Lesson

Fractions

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Fractions, Decimals and Percentages are different ways of expressing the same information

Let’s look at that!

If we think of this as a pizza and the

shaded bit is the bit you are being

given we can say that this is a half

[pic] circle is broken up into 2 bits

There is one part shaded (or selected)

If I gave you the whole pizza then I would have given you

[pic] or 1 pizza. So 1 pizza is equal to [pic]

Example 1:

What fraction / decimal or percentage is shown below?

[pic]

Example:

Decimals

In a similar way to convert fractions or percentages to decimals we follow the sum. The line in the middle of a fraction means the same thing as divided by.

So if we have [pic], this means 50 divided by 100.

100[pic] which will work out to give you 0.5.

Try some of the other examples above!

Adding and Subtracting Fractions

Let me tell you a story…..

Dominos has a 2 for Tuesdays deal where you buy 2 pizzas but only pay for one.

My wife brought home 2 pizzas and asked me to cut up one while she cut up the other.

I cut mine in half and my wife (being the good mother) cuts hers up in 3 (one for me, one for her and one for the kids for lunch tomorrow).

How can I work out how much pizza I received?

Example:

[pic]

Fraction of an Amount

When finding the fraction of an amount it appears the second number is not a fraction. Whole numbers can be written as a fraction over 1.

Like: [pic]. Then you multiply the top and bottom and simplify. Ie top two numbers multiplied together give the top part of the fraction, bottom two number give the bottom

[pic]

• 2 x 50 = 100

• 5 x 1 = 5

• [pic]

• How many 5’s in 100? = 20

Example:

Calculate:

[pic]

Examples:

a) [pic]

b) [pic]

c) [pic]

[pic]

Simplifying Fractions

To simplify a fraction, find the Highest common factor between the 2 numbers and divide top and bottom by that number.

This is sometimes called Equivalent Fractions.

Vulgar and improper Fractions

[pic]

This is 5 full pizzas (with 8 slices in each) and a pizza with 7 slices only so to write it as vulgar or sometimes known as top-heavy fraction

5 x 8 = 40

40+7 = 47 slices

Therefore the entire fraction is : [pic]

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