What are the least common factor of 10 and 21?

Answer 1

The least common factor is a term often mistakenly given to either the greatest common factor (GCF) or the least common multiple (LCM). This term is not often used because it does not describe a useful relationship between numbers. Since 1 evenly divides all integers, 1 is technically the least common factor for any set of integers.

The smallest non-one common factor of 7 and 21 is 7.
The Lowest Common Factor of any set of numbers is 1.

I suspect this is not what you want. There are:

Lowest Common Multiple which is the lowest (positive) whole number which is a multiple of all the numbers; LCM(7, 21) = 21 (3 × 7 = 21, 1 × 21 = 21);

Highest Common Factor which is the largest (positive) whole number which divides into all the numbers without remainder, that is is a factor of all the numbers; HCF(7, 21) = 7 (7 = 1 × 7, 21 = 3 × 7).

Answer 2

The least common factor of any set of positive integers is 1.

Answer 3

The least common factor is 1. (The least common factor of any two or more positive integers is always 1.)

Answer 4

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