Activity › Discussion › Math › Fraction › Reply To: Fraction

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When adding fractions with different denominators, you need to find a common denominator before performing the addition. The common denominator is the least common multiple (LCM) of the denominators involved. Once you have the common denominator, you can add the numerators and keep the common denominator unchanged. Here’s a stepbystep process:
Identify the denominators of the fractions you want to add.
Find the least common multiple (LCM) of the denominators. This is the smallest number that both denominators divide into evenly.
Convert each fraction so that they have the common denominator. To do this, multiply the numerator and denominator of each fraction by the same value that will make the denominator equal to the common denominator found in step 2.
Once the fractions have the same denominator, add the numerators together and write the sum over the common denominator.
Simplify the resulting fraction, if needed, by reducing it to its simplest form.
For example, let’s add 1/3 and 2/5:
Step 1: The denominators are 3 and 5.
Step 2: The LCM of 3 and 5 is 15.
Step 3: Convert 1/3 to an equivalent fraction with a denominator of 15: (1/3) x (5/5) = 5/15. Convert 2/5 to an equivalent fraction with a denominator of 15: (2/5) x (3/3) = 6/15.
Step 4: Add the numerators: 5/15 + 6/15 = 11/15.
Step 5: The fraction 11/15 is already in its simplest form.
So, 1/3 + 2/5 = 11/15.