The highest common factor is 14.
- The factors of 98 are 98, 49, 14, 7, 2, 1.
- The factors of 42 are 42, 21, 14, 7, 6, 3, 2, 1.
- The common factors of 98 and 42 are 14, 7, 2, 1, intersecting the two sets above.
- In the intersection factors of 98 ∩ factors of 42 the greatest element is 14.
- Therefore, the highwat common factor of 98 and 42 is 14.