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Published bySilas Wilkinson Modified over 8 years ago
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Fractions Fractions are a way of showing a portion of material compared with the whole thing. E.g. ½ Pizza, half time, 1/3 off.
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Simplifying Fractions Sometimes when you do a calculation involving fractions you get an answer that must be simplified. To do this you divide top and bottom numbers by the SAME number and repeat using various numbers (2, 3, 5, etc.) until you cannot divide any further !!!
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Simplifying Fractions Remember that you must treat top and bottom numbers identically !!! Example: Simplify
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Divide top and bottom by 5 giving We can divide by 5 again, giving So, Simplifies to give So are all the same fraction They are called equivalent fractions 5 20
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Now you try the following:
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Sometimes a fraction is “top heavy” like: In these cases, divide the top by the bottom leaving a remainder. The main number is integer (whole numbers) the remainder is still a fraction. Now simplify the remaining fraction part as before. 3 r 2
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Now you try the following:
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Adding Fractions + = + =
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Why Not ??????????? +=
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Fractions can only be added or subtracted if the denominators are the same. + += 3 / 5 + 1 / 5 = 4 / 5 Common denominators
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1/41/4 1/31/3 + 1/41/4 1/31/3 += ? 1/41/4 1/31/3 + = 3 / 12 + 4 / 12 = 7 / 12
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Addition of Fractions Addition of fractions is a little complicated, BUT providing you follow the procedure you should not have too much difficulty. First multiply the bottom numbers 5 × 3 Now cross multiply as follows (2 × 3) + (5 × 1) Work out = = Is it possible to simplify?
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Now you try the following:
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Subtraction of Fractions This is virtually identical to the addition of fractions. The only difference is that the addition sign is replaced by subtraction. BUT remember to do the cross- multiplying in the right order (as shown, down before up).
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Multiply the bottom line. 5 × 4 Now cross multiply (3 × 4)–(5 × 1) Work it out = = Finally check if the fraction can be simplified!! In this case, NO
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Now you try the following:
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Multiplication of Fractions This is best done by example: We do straight line multiplying = = Simplifying HOW?
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Now you try the following:
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Division of Fractions This is similar to multiplication but involves one more step first!! Change the ÷ to a × and turn the second fraction upside down. Now multiply as before = Simplifying
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Now you try the following:
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Converting fractions to decimals Simple….. Just divide the top number by the bottom!!! 3 ÷ 4 0.75 ?
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Now you should try questions from either the green textbook or the white workbook.
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Divide top and bottom by 5 giving We can divide by 5 again, giving 5 20 Simplifying Fractions are all the same fraction They are called equivalent fractions Sometimes a fraction is “top heavy” like In these cases, divide the top by the bottom leaving a remainder. The main number is integer (whole numbers) the remainder is still a fraction. Now simplify the remaining fraction part as before. :
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Addition of Fractions Addition of fractions is a little complicated,BUT providing you follow the procedure you should not have too much difficulty. First multiply the bottom numbers 5 × 3 Now cross multiply as follows (2 × 3)+(5 × 1) Work out = = Is it possible to simplify? Multiply the bottom line. Now cross multiply (3 × 4) – (5 × 1) = 5 × 4 Subtraction of Fractions
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Multiplication of Fractions We do straight line multiplying Division of Fractions This is similar to multiplication but involves one more step first!! Change the ÷ to a × and turn the second fraction upside down. Now multiply as before
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