4.6 repeating decimals

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This lesson contains 14 slides, with text slides.

time-iconLesson duration is: 50 min

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Slide 1 - Slide

Today
- I understand the differences between natural, whole, rational, irrational and real numbers.
- I understand what a repeating decimal is and know the line notation involved.


Slide 2 - Slide




I'll show you how this works.
ab=ab
ba=ba

Slide 3 - Slide

A repeating decimal


We can write this as
31=0,333...

Slide 4 - Slide

Two other examples

Slide 5 - Slide

All numbers with repeating decimals can be written as a fraction.

We can always convert a repeating decimal to a fraction using the following fun algorithm:

Slide 6 - Slide

Consider 0,99999...
Let a = 0,999...

Slide 7 - Slide

Consider 0,99999...
Let a = 0,999...
then 100a = 99,999...

Slide 8 - Slide

Consider 0,99999...
Let a = 0,999...
then 100a = 99,999...

100a - a = 99a




Slide 9 - Slide

Consider 0,99999...
Let a = 0,999...
then 100a = 99,999...

100a - a = 99a
and
99,999... - 0,999... = 99



Slide 10 - Slide

Consider 0,99999...
Let a = 0,999...
then 100a = 99,999...

100a - a = 99a
and
99,999... - 0,999... = 99
so 99a = 99 and this means 



a=9999=1

Slide 11 - Slide

Another example

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Practice!
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Slide 14 - Slide