What is the HCF of 81 243 and 1215?
To find the highest common factor (HCF) of 81, 243, and 1215, we first need to find the prime factorization of each number. The prime factorization of 81 is 3^4, 243 is 3^5, and 1215 is 3^5 * 5. To find the HCF, we look for the highest power of each prime factor that appears in all the numbers. In this case, the highest power of 3 that appears in all three numbers is 3^4, so the HCF of 81, 243, and 1215 is 81.