# Finding the LCM Least Common Multiple - PowerPoint PPT Presentation

Finding the LCM Least Common Multiple

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Finding the LCM Least Common Multiple

## Finding the LCM Least Common Multiple

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1. Finding the LCMLeast Common Multiple The LCM is the Lowest Number that is a Multiple of Both Numbers. Ex. The LCM of 12 & 9 is 36 since both 12 & 9 divide evenly into 36. Hint: Think of Common Denominators in Fractions. A common denominator is the LCM of the denominators.

2. Finding Least Common Multiple Find LCM of 45 & 75

3. Finding Least Common Multiple Find LCM of 45 & 75 45 75 Complete Factor Tree for both numbers. 25 3 5 9 5 • 3 • 3 5 • 5 • 3

4. Finding Least Common Multiple Find LCM of 45 & 75 45 75 Complete Factor Tree for both numbers. Identify Common Factors. 25 3 5 9 5 • 3 • 3 5 • 5 • 3 THE COMMON FACTORS ARE 5 & 3

5. Finding Least Common Multiple Find LCM of 45 & 75 45 75 Complete Factor Tree for both numbers. Identify Common Factors. Multiply Common Factors with ALL OTHER FACTORS 25 3 5 9 5 • 3 • 3 5 • 5 • 3 THE COMMON FACTORS ARE 5 & 3 OTHER FACTORS LCM = CF’s•ALL OTHER FACTORS LCM = 5•3 • 5 • 3 = 225

6. Finding the LCMLeast Common Multiple(FOR 3 NUMBERS) Find LCM of 225, 10 & 66

7. Finding the LCMLeast Common Multiple(FOR 3 NUMBERS) Find LCM of 225, 10 & 66 225 Complete Factor Tree for all numbers. 10 66 5 45 5 • 2 11 6 5 9 11 • 3 • 2 5 • 5 • 3 • 3

8. Finding the LCMLeast Common Multiple(FOR 3 NUMBERS) Find LCM of 225, 10 & 66 225 Complete Factor Tree for all numbers. Identify Common Factors OF ANY 2 #’S. 10 66 5 45 5 • 2 11 6 5 9 11 • 3 • 2 5 • 5 • 3 • 3 THE COMMON FACTORS ARE 2,5 & 3

9. Finding the LCMLeast Common Multiple(FOR 3 NUMBERS) Find LCM of 225, 10 & 66 225 Complete Factor Tree for all numbers. Identify Common Factors OF ANY 2 #’S. Multiply Common Factors with ALL OTHER FACTORS 10 66 5 45 5 • 2 11 6 5 9 11 • 3 • 2 5 • 5 • 3 • 3 THE COMMON FACTORS ARE 2,5 & 3 OTHER FACTORS LCM=2•5•3•5•3•11=4950