Finding Common Denominators
What is a denominator? –The bottom part of a
fraction that represents the total parts of the whole
6/6
What is a common denominator? – The possible
ways that fractions can be used to add or subtract
unlike numbers. They can ONLY be solved by finding
a common denominator.
Multiples- the product of a whole number
multiplied times any other whole number.
Ex: Some multiples of 6:
6, 12, 18, 24, 30, 36, 42
Common Multiple- a number that is a multiple of
two or more numbers
Ex: Some multiples of 3 & 6:
6, 12, 18, 24, 30, 36, 42
Least Common Multiple- the smallest common
multiple of a set of two or more numbers. Lowest
multiple that two numbers have in common.
EX:
5= 5, 10, 15, 20 25, 30
6= 6, 12, 18, 24, 30, 36
TO ADD AND SUBTRACT FRACTIONS WITH UNLIKE
DENOMINATORS…
STEP 1: Find the multiples of each denominator
STEP 2: Compare the lists of multiples. Circle the
common multiples between the two lists.
SHORTCUT for L.C.D.
Check to see if the smaller denominator divides
evenly into the larger denominator.
If it does, use the larger denominator for
Your LCDn .