The greatest common factor (GCF) of 24 and 36 is 12. This can be found using various methods such as prime factorization, listing common factors, or long division. By prime factorization, the common prime factors of 24 and 36 are 2 and 3, and multiplying these gives the GCF of 12. Similarly, listing the common factors of 24 and 36 reveals that 12 is the greatest common factor. Long division can also be used to find the GCF, and it will result in 12 as well.