Why do we use LCM when adding fractions?

Adding Fractions: If the denominators are not the same, you must find the common denominator by finding the least common multiple (LCM). Subtracting Fractions: If the denominators are not the same, you must find the common denominator by finding the least common multiple (LCM).

Why do denominators have to be the same when adding fractions?

If you’re adding two fractions with a common denominator, you can combine them together by adding the numerators together (the top numbers). The denominator will always stay the same because the size of the equal pieces does not change when you combine the two fractions together.

Why do we need to find the least common denominator in adding dissimilar fractions?

When we add or subtract fractions, their denominators need to be same or common. If they are different, we need to find the LCD (least common denominator) of the fractions before we add or subtract. This gives the LCD of the fractions.

How is the LCM related to fractions?

LCM is a fraction greater than both the fractions or equal to one or both of them (when both fractions are equal). When you take the LCM of the numerator and GCF of the denominator, you are making a fraction greater than (or equal to) the numbers.

Do you add the denominator when adding fractions?

To add fractions there are Three Simple Steps: Step 1: Make sure the bottom numbers (the denominators) are the same. Step 2: Add the top numbers (the numerators), put that answer over the denominator. Step 3: Simplify the fraction (if possible)

How can you use LCM to add or subtract fractions with different denominators?

Make their denominators equal using the concept of least common multiple. Then subtract their numerators accordingly. Rewrite each fraction to its equivalent fraction with a denominator equal to the LCM = 30, then subtract their numerators. Make sure to reduce your answer to the lowest term.

How do you get the least common denominator?

To find the least common denominator, list out the multiples of both denominators until you find the smallest multiple that is shared by both. Because 20 is the first shared multiple of 4 and 5, it must be the least common denominator for these two fractions.

How do you find the lowest common denominator of a fraction?

To find the lowest common denominator, we see if the larger denominator (20) can be divided by the smaller denominator (4). We then need to work out what we need to multiply the 4 by, to make 20 (this is 5). Therefore, we multiply 1/4 by 5, so that it becomes 5/20. You can then add 5/20 and 3/20 which makes 8/20.

How do you use LCM to compare fractions with different denominators?

How can we compare fractions when the numerators and denominators are different? Change them to equivalent fractions that will have equal denominators. As the common denominator, choose the LCM of the original denominators. Then the larger the numerator, the larger the fraction.