What is the least common factor of 28 and 54?

Answer: 1

The factors of 28 are 1, 2, 4, 7, 14, and 28.

The factors of 54 are 1, 2, 3, 6, 9, 18, 27, and 54.

The common factors are 1 and 2; the least (or smallest) common factor is 1.