Final answer:
The highest common factor (HCF) of 72 and 98 is 2.
Step-by-step explanation:
To find the highest common factor (HCF) of 72 and 98, we need to find the greatest number that can divide evenly into both 72 and 98. One way to do this is to list the factors of each number. For 72, the factors are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, and 72. For 98, the factors are 1, 2, 7, 14, 49, and 98. The highest common factor is the greatest number that appears in both lists, which is 2. Therefore, the HCF of 72 and 98 is 2.