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Least Common Multiple or Least Common Denominator




Objective: I can find the least common multiple or least common denominator.


One way to find the least common multiple (LCM) is

Step 1: List the multiples of the given numbers.

Step 2: Find the multiples common to the given numbers.

Step 3: Select the smallest common multiple.


Read the lesson on least common multiple if you need to learn how to find the lowest common multiple.


We can use the least common multiple when adding or subtracting fractions with unlike denominators. It is then called the least common denominator.


Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Find the LCM of the following numbers:

a) 4, 6 and 30
LCM =

b) 8, 12 and 20
LCM =

c) 10, 20 and 25
LCM =

d) 12, 15 and 24
LCM =

e) 8, 15 and 24
LCM =

f) 12, 16 and 25
LCM =

g) 20, 30 and 45
LCM =

h) 32, 48 and 80
LCM =

i) 14, 16 and 56
LCM =

j) 15, 18, 42
LCM =





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