Adult Numeracy Level 2 Division of Decimals (and by decimals) Dave Cross, Suffolk New College
Decimals at Level 2 <ul><li>At level 2 we should be able to divide decimals up to three decimal places (ref N2/L2.6) and divide numbers of any size using efficient written and mental methods (Ref; N1/L2.1) </li></ul><ul><li>A Decimal place is the position of the digit to the right of the decimal point, you should recognise these values as tenths, hundredths, and thousandths </li></ul>
Decimals at Level 2 <ul><li>For example; Let’s consider a piece of cloth that measures 126cm long, in metres this is 1.26m. </li></ul><ul><li>If we were then to cut this length into three equal lengths we are required to divide 1.26 by 3 to give us the length of each piece of cloth </li></ul>
Dividing decimals by whole numbers(recap) Let us look at two ways of showing this calculation First; as a fraction 1.26 3 This doesn’t appear that helpful, except to see that our answer is less than 1 The next slide shows the second method
Dividing decimals by whole numbers(recap) Secondly; set out in the traditional way 0.4 2 So here we have used division by whole numbers To find the length of each cut to be 0.42m But what if we want to find how many 3cm strips we can obtain from the 1.26m cloth?
Dividing decimals by decimals <ul><li>To find the number of 3cm lengths we can get from a 1.26m long cloth </li></ul>As a fraction, we have 1.26 0.03 The golden rule for equivalent fractions; “ Whatever we multiply or divide the top by We must multiply or divide the bottom by”
Dividing decimals by decimals <ul><li>So to find the number of 3cm lengths we can get from a 1.26m long cloth </li></ul>1.26 = 126 = 0.03 3 So on this occasion we can get 42 strips of 3cm long cloth from an original length 0f 1.26m
Summary <ul><li>We can already divide by whole numbers </li></ul><ul><li>So when dividing by decimals, if we imagine the calculation set out as a fraction we need to change the denominator into a whole number </li></ul><ul><li>We do this by employing the golden rule top and bottom, then do the division </li></ul><ul><li>There is no need to replace the decimal points in the way that we do in multiplication as we have employed the golden rule of equivalent fractions </li></ul>
Try some examples for yourselves <ul><li>0.342/0.6=? </li></ul><ul><li>3.68 divided by 4.8=? </li></ul><ul><li>3.43/0.03=? </li></ul>56.8/0.008=? Use a calculator to check you answers
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