6th Grade Math Textbook, Fundamentals

XVI.Add and Subtract Fractions

To add fractions:

• Find the least common denominator
  (LCD) of the fractions.


• Rename each fraction as an equivalent
  fraction with the LCD as the denominator.


• Add. Express the sum in simplest form.

To subtract fractions:

• Find the least common denominator
  (LCD) of the fractions.


• Rename each fraction as an
  equivalent fraction with the LCD
  as the denominator.


• Subtract. Express the difference
  in simplest form.

XVII.Multiply Fractions

To multiply fractions:

• Multiply the numerators. Then multiply
  the denominators.


• Write the product in simplest form.

To multiply fractions using the greatest common factor (GCF):

• Divide anynumerator and denominator
  by their GCF.


• Multiply the numerators. Then multiply
  the denominators. The product will be
  in simplest form.

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 6NLOOV8SGDWH

Add: 

Multiples of 4: 4, 8, 12, 16,...

Multiples of 3: 3, 6, 9, 12, 15,...

The LCD is 12.

2

3

3

4

Think

The LCD is the least common multiple

(LCM) of the denominators.



 

1217 ^1125

8

12

2   4

3   4

9

12

2

3

3   3

4   3

3

4

Subtract: 

LCD of^12  101 : 10

1

10

1

2





104 ^25 simplest form

1

10

5

10

1

10

1   5

2   5

1

2

Multiply:

     

246  246 ^6641 simplest form

2   3

3   8

3

8

2

3

3

8

6

24

2

3

     Divide by the GCF.



 simplest form

2

3

3

8

1

1 4

1

1

4

1   1

1   4

3

8

2

3