Basic Algebra/Working with Numbers/Multiplying

Vocabulary Lesson Multiplication of rational fractions is perhaps easier than addition and subtraction (lessons 4 and 5). This is because the denominators do not have to be equal, so you do not need to find a common denominator before carrying out a calculation. Consider the following problem: This may look like a difficult calculation but in reality it's rather easy. We simply multiply the two numerators together, then multiply the denominators. So, the answer to the above problem would be: This fraction is irreducible as 35 and 36 share no common factors. Notice that in the problem above there was a top heavy fraction (). When multiplying two fractions, if one is top heavy then leave it as it is until you have your final answer. Attempting to multiply a mixed number with a fraction will result in an incorrect answer. Let us now consider a more complex problem. Say we had three large fractions which we had to multiply together: The first thing you should notice is that can be simplified to . This should make this calculation a little easier. As above, we simply multiply the numerators together then multiply the denominators together. Now this is a huge number so trying to find common factors in order to reduce it will be very difficult and time consuming. If you have a scientific calculator to hand, simply enter the above fraction and it should give you an irreducible fraction out. My calculator gives the following result: Practice Problems Use / as the fraction line! { |type="{}"} { 50/84|25/42_13 } { |type="{}"} { 3/4_13 } { |type="{}"} { 4000/8|4,000/8|1000/2|1,000/2|500/1|500_13 } { |type="{}"} { 1250/75000|1,250/75,000|2/120|1/60_13 } { |type="{}"} { 12000/85000|12,000/85,000|60/425|12/85_13 } Basic Algebra Multiplying Rational Numbers Subtracting Rational Numbers Distributive Property