What is the hcf of 4 and 5 and 6?

Oh, what a happy little question! The highest common factor (HCF) of 4, 5, and 6 is 1. You see, they don't have any other factors in common other than 1, which makes them unique and special in their own way. Just like each tree in a forest, they stand tall and proud on their own, yet still part of the beautiful mathematical landscape.