What is the least common factor of 24 and 36?

The factors of 24 are 1, 2, 3, 4, 6, 8, 12, and 24.

The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36.

The common factors of 24 and 36 are 1, 2, 3, 4, 6, and 12. Therefore, the least (smallest) common factor is 1.
The lowest common factor of any set of positive integers is 1.
The least common factor of any set of integers is 1.