6th Grade Math Textbook, Progress

Find the LCM of each set of numbers.

1. 3, 4 2. 3, 6 3. 2, 5 4. 8, 24 5. 12, 15


2. 4, 10 7. 1, 9 8. 6, 5 9. 12, 10 10. 40, 16


3. 3, 4, 6 12. 1, 6, 7 13. 4, 5, 10 14. 4, 6, 8


4. 5, 6, 12 16. 3, 9, 12 17. 8, 12, 36 18. 10, 18, 72


5. 4, 6, 9 20. 5, 10, 15 21. 3, 5, 9 22. 8, 9, 10

Update your skills. See page 3.

Least Common Multiple

6-9

The planet Jupiter takes 12 years to make

one complete revolution around the Sun.

The planet Saturn takes 30 years to make

one complete revolution around the Sun.

If both planets are aligned tonight, how

many years will it be before they have the

exact same position in the sky again?

To find the number of years, you must find

the least common multiple (LCM)of

12 and 30.

The least common multiple of two or more

numbers is the least number, except 0,

that is a common multiple of both (or all)

of the numbers.

Multiples of 12:12, 24, 36, 48, 60 , 72,...

Multiples of 30:30, 60 , 90, 120, 150, 180,...

The least common multiple (LCM) of 12 and 30 is 60.

So Jupiter and Saturn will have the exact same position

in the sky in 60 years.

Extend the list until you find a common

multiple of the numbers.

2.4

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