Answer:
LCM - 1
HCF - 3
Explanation:
LCM - Lowest Common Factors
HCF - Highest Common Factors
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Factors of 15 - 1, 3, 5, 15
Factors of 42 - 1, 2, 3, 6, 7, 14, 21, 42
Factors of 123 - 1, 3, 41, 123
So now we know the factors of 15, 42, 123 what is lowest and highest factor we can find in every number
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I have bolded the lowest and highest common factor.
Factors of 15 - 1, 3, 5, 15
Factors of 42 - 1, 2, 3, 6, 7, 14, 21, 42
Factors of 123 - 1, 3, 41, 123
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LCM - 1
HCF - 3