math unit1 decimals and fractions

$: Math unit1 decimals and fractions$
Unit 1Decimals & Fractions

Presentation 1 Multiplying and Dividing Decimals

Presentation 2 Converting Fractions and Decimals

Presentation 3 Negative Numbers

Presentation 4 Operations with Negative Numbers

Presentation 5 Estimating Answers


Multiplying and Dividing Decimals

To multiply by 100, move the decimal point 2 places to the right, giving:

similarly

To divide by 100, move the decimal point 2 places to the left, giving:

similarly

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Multiplying and Dividing Decimals

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Unit 1Decimals & FractionsConverting Fractions and

Decimals

Fractions to Decimals

Express as a decimal.

Here it is best to divide out:

Express as a decimal.

Here it is easier to make the denominator a multiple of 10

Express as a decimal in its simplest form


Converting Fractions and Decimals


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Negative Numbers

Example 1

What is 15oC less than 26oC?

Solution

26oC – 15oC = 11oC

Example 2

What is 15oC less than 10oC?

Solution

10oC – 15oC = – 5oC


Negative Numbers


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Unit 1Decimals & FractionsOperations with Negative

Numbers

Remember …

Example 1

Remember …

Example 2

Remember …

Example 3

Remember …

Example 4


Operations with Negative Numbers


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Estimating Answers

It is important to be able to estimate answers to complex calculations.

Without a calculator which of the answers is equal to ?

A 1∙649 B 16∙494 C 164∙945

Without a calculator which of the answers is equal to ?

You have to approximate each answer in the calculation. Hence, for example

A 1∙649 B 16∙494 C 164∙945


Estimating Answers


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math unit1 decimals and fractions

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