Let's solve each problem step by step to find the
Least Common Multiple (LCM) using the
multiples of each number.
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🔹 Problem 1: LCM of 7 and 9
Step 1: List the multiples of each number:
- Multiples of 7:
7, 14, 21, 28, 35, 42, 49,
63, 70, ...
- Multiples of 9:
9, 18, 27, 36, 45, 54,
63, 72, ...
Step 2: Find the smallest common multiple.
→ The first common multiple is
63.
✔ LCM = 63
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🔹 Problem 2: LCM of 10 and 9
Multiples of 10:
10, 20, 30, 40, 50, 60, 70, 80, 90, 100, ...
Multiples of 9:
9, 18, 27, 36, 45, 54, 63, 72, 81,
90, ...
First common multiple: 90
✔ LCM = 90
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🔹 Problem 3: LCM of 9 and 8
Multiples of 9:
9, 18, 27, 36, 45, 54, 63, 72, 81, ...
Multiples of 8:
8, 16, 24, 32, 40, 48, 56, 64,
72, ...
First common multiple: 72
✔ LCM = 72
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🔹 Problem 4: LCM of 6 and 5
Multiples of 6:
6, 12, 18, 24, 30, 36, ...
Multiples of 5:
5, 10, 15, 20, 25,
30, ...
First common multiple: 30
✔ LCM = 30
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🔹 Problem 5: LCM of 5 and 4
Multiples of 5:
5, 10, 15, 20, 25, ...
Multiples of 4:
4, 8, 12, 16,
20, ...
First common multiple: 20
✔ LCM = 20
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✔ Final Answers:
1. LCM of 7 and 9 =
63
2. LCM of 10 and 9 =
90
3. LCM of 9 and 8 =
72
4. LCM of 6 and 5 =
30
5. LCM of 5 and 4 =
20
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Let me know if you'd like a visual chart or explanation using prime factorization!
Parent Tip: Review the logic above to help your child master the concept of least common multiple worksheet 4th grade.
