| GCF -- the greatest common factor is the biggest factor that two or more numbers share in their list of factors, or the product of their common prime factors. |
| LCM -- the least common multiple is the smallest multiple shared by two or more numbers, or the product of their factors without double counting the common factors. |
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Relatively prime -- two numbers are relatively prime if they have no common factors except the number one. Warning: these are not always prime numbers, but they have a prime relationship with each other. For example, 6 and 7 are relatively prime numbers, but so are 45 and 64. |