## Monday, March 12, 2007

### There are 3 Simple Steps to add fractions:

Step 1: Make sure the bottom numbers (the denominators) are the same

Step 2: Add the top numbers (the numerators). Put the answer over the the same denominator as in step 1

Step 3: Simplify the fraction.

### Example 1:

 1 + 1 4 4

Step 1. The bottom numbers are already the same. Go straight to step 2.

Step 2. Add the top numbers and put the answer over the same denominator:

 1 + 1 = 1 + 1 = 2 4 4 4 4

Step 3. Simplify the fraction:

 2 = 1 4 2

(If you are unsure of the last step see the equivalent fractions page)

### Example 2:

 1 + 1 3 6

Step 1. The bottom numbers are now different. We need to make them the same:

 1 = 2 3 6

Step 2. Add the top numbers and put them over the same denominator:

 2 + 1 = 2 + 1 = 3 6 6 6 6

Step 3. Simplify the fraction:

 3 = 1 6 2

## Adding Fractions with Different Denominators

To Add Fractions with different denominators:

• Find the Lowest Common Denominator (LCD) of the fractions
• Add in the new numbers to the fractions to have the LCD
• Add the numerators of the fractions
• Simplify the Fraction

Example: Find the Sum of 2/9 and 3/12

• Determine the Greatest Common Factor of 9 and 12 which is 3
• Either multiply the denominators and divide by the GCF (9*12=108, 108/3=36)
• OR - Divide one of the denominators by the GCF and multiply the answer by the other denominator (9/3=3, 3*12=36)
• Rename the fractions to use the Least Common Denominator(2/9=8/36, 3/12=9/36)
• The result is 8/36 + 9/36
• Add the numerators and put the sum over the LCD = 17/36
• Simplify the fraction if possible. In this case it is not possible

@ pictures from various sites

#### 1 comment:

Shirzuki said...

and i'm still confused!!!!! this is so freakin hard!!!!