Answer:
By Prime Factorization, GCF of (81,54) is 27.
Explanation:
First we will factorize the number 81 such as

which are the prime factors of 81
similarly prime factor for number 54 will be

which are the prime factors for 54
GCF is the greatest common factor i.e all the common factors will be multiplied therefore,

Hence GCF(81,56) is 27.