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it is necessary when comparing fractions, like when you are trying to figure out which fraction is bigger, 3/4 or 5/8. you multiply the denominators, 4x8, and the answer is possibly the least common denominator. then you multiply one of the old denominators to the other numerator, and do the same the other way, 4x5 and 8x3. those are the new numerators. the new fractions are 24/32 and 20/32. 3/4 is bigger!
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When adding fractions with unlike denominators it is most helpful if the fractions are renamed using the?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator.
How do you add and subtract fractions with no common denominator?
You convert them to equivalent fractions with the a common denominator. This new denominator must be a common multiple of the denominators. The Least Common Multiple (LCM) may be a recommendation but is not necessary. However, using the LCM will keep all the numbers as small as possible and that may be an advantage.
What is the difference between a least common multiple and a least common denominator?
The Least (or Lowest) Common Multiple (LCM) is the smallest number that is a multiple of both numbers. For example: the LCM of 10 and 4 is 20, because both 10 and 4 go into 20 and 20 is the smallest number both 10 and 4 can go into. To be able to add or subtract fractions they must have the same denominator. If the denominators are different then the fractions must first be converted into equivalent fractions with a common denominator; any common denominator can be used, but by using the Least Common Multiple of the denominators as the new denominator it keeps the numbers smaller; this smallest denominator is known as the Least Common Denominator Thus the Least Common Denominator is the Least Common Multiple of the denominators of two (or more) fractions (used when adding or subtracting fractions with different denominators). As the Least Common Multiple is used most often with adding or subtracting fractions, it is often referred to as the Least Common Denominator (because the numbers being considered are usually denominators of fractions).
What is the rule for adding fractions with unlike denominators?
You convert them, using equivalent fractions, so that they have the same denominator - a common multiple of the deniminators. Then the denominator of the sum is the common multiple while the numerator is the sum of numerators of the converted fractions. Finally, you need to check if the answer can be simplified. Students are often instructed that they must use the least common multiple (LCM). This is not necessary: any common multiple will do, though the LCM will require smaller numbers and so may be easier.
What is the least common multiple of 10 18 21 by using by using prime factors?
The Least Common Multiple of 10, 18, 21 is 630.
