Fraction XAdding Unlike Denominators: Fraction X Adding Unlike Denominators By Monica Yuskaitis


Reminder: Reminder Be sure to do Fractions IX before continuing with this lesson.


Common Multiple: Common Multiple A number that is a multiple of two or more numbers. Some multiples of 3 andamp; 6 6, 12, 18, 24, 30, 36, 42


Least Common Multiple: Least Common Multiple The smallest common multiple of a set of two or more numbers. 6 = 6, 12, 18, 24, 30, 36 5 = 5, 10, 15, 20, 25, 30


Shortcut for Finding the Least Common Denominator or Least Common Multiple: Shortcut for Finding the Least Common Denominator or Least Common Multiple 1 3 1 9 + Check to see if the smaller denominator divides evenly into the larger denominator. If it does, use the larger denominator for your LCD or LCM. 3 will divide evenly into 9, so 9 is your LCD or LCM.


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Find the multiples of each denominator. 1 = 5, 10, 15, 20, 25, 30 1 = 10, 20, 30, 40, 50 + 5 10


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Compare the lists of multiples. Circle the common multiples between the two lists. 1 5 = 5, 10, 15, 20, 25, 30 1 10 = 10, 20, 30, 40, 50 +


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Use the lowest common multiple as the denominator. 1 5 = 5, 10, 15 ,20 ,25 ,30 1 10 = 10, 20, 30, 40, 50 +


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators This number is also called the least common denominator. 1 5 = 5, 10, 15 ,20 ,25 ,30 1 10 = 10, 20, 30, 40, 50 +


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Rewrite the fractions using the least common denominator or least common multiple. 1 5 1 10 + 10 10


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Find the equivalent fractions for 1/5 andamp; 1/10 with 10 as the denominator. 1 5 1 10 + 10 10 You know that 1/10 is equal to 1/10 so Put a 1 over the Bottom 10. 1


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Find the equivalent fractions for 1/5 andamp; 1/10 with 10 as the denominator. 1 5 1 10 + 10 10 To find the top number, ask yourself what do you multiply the 5 by to get 10. 1


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Find the equivalent fractions for 1/5 andamp; 1/10 with 10 as the denominator. 1 5 1 10 + 10 10 That’s right 2. Since you are looking for the equivalent fraction you know the top number must also be multiplied by 2. 1 x 2 = x 2 =


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Find the equivalent fractions for 1/5 andamp; 1/10 with 10 as the denominator. 1 5 1 10 + 10 10 To find the top number just multiply 2 x 1 to get your equivalent fraction. 1 x 2 = x 2 = 2


To Add or Subtract Fractions With Unlike Denominators: To Add or Subtract Fractions With Unlike Denominators Now just add the numerators. 1 5 1 10 + 10 10 Remember when adding fractions you never add the denominators. 1 x 2 = x 2 = 2 10 3


Add these Fractions: Add these Fractions 1 2 1 8 + Use the short cut to find the Least Common Denominator (LCD). 8 8


Add these Fractions: Add these Fractions 1 2 1 8 + Now find the equivalent fractions for 1/2 andamp; 1/8. 8 8 x 1 = x 4 = Ask what do you multiply 2 by to get 8 and what do you multiply 8 by to get 8.


Add these Fractions: Add these Fractions 1 2 1 8 + Since you are writing equivalent fractions, now multiply the top numbers by the same number you did in the bottom. 8 8 x 1 = x 4 = x 1 = x 4 =


Add these Fractions: Add these Fractions 1 2 1 8 + Now multiply across. 8 8 x 1 = x 4 = x 1 = x 4 = 1 4


Add these Fractions: Add these Fractions 1 2 1 8 + Add your new numerators. 8 8 x 1 = x 4 = x 1 = x 4 = 1 4 5 8


Add these Fractions: Add these Fractions 2 5 1 3 + Find the common Multiples for 5 and 3. Write This number As your new denominator. 15 15


Add these Fractions: Add these Fractions 2 5 1 3 + Ask yourself what you multiply the bottom number by to get 15. 15 15 x 5 = x 3 =


Add these Fractions: Add these Fractions 2 5 1 3 + Multiply the top number by the same number you did in the bottom. 15 15 x 5 = x 3 = x 5 = x 3 =


Add these Fractions: Add these Fractions 2 5 1 3 + Multiply across. 15 15 x 5 = x 3 = x 5 = x 3 = 5 6


Add these Fractions: Add these Fractions 2 5 1 3 + Now add your new numerators. 15 15 x 5 = x 3 = x 5 = x 3 = 5 6 11 15


Add these Fractions: Add these Fractions 1 6 1 4 + 12 12 x 3 = x 2 = x 3 = x 2 = 3 2 5 12


Add these Fractions: Add these Fractions 5 6 1 8 + 24 24 x 3 = x 4 = x 3 = x 4 = 3 20 23 24


Add these Fractions: Add these Fractions 2 3 1 9 + 9 9 x 1 = x 3 = x 1 = x 3 = 1 6 7 9


Add these Fractions: Add these Fractions 4 5 2 3 + 15 15 x 5 = x 3 = x 5 = x 3 = 10 12 22 15


Simplify Your Answer: Simplify Your Answer 22 15 15) 22 1 15 7 7 15