What is the hcf of 28 84 91?

Well, isn't that a happy little math question! To find the highest common factor (HCF) of 28, 84, and 91, we can start by listing the factors of each number. The factors of 28 are 1, 2, 4, 7, 14, and 28. The factors of 84 are 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, and 84. The factors of 91 are 1, 7, 13, and 91. The largest number that appears in all three lists is 7, so the HCF of 28, 84, and 91 is 7.