Final answer:
The least upper bound of elements 8 and 12 in the given set is 24, as it is the smallest number in the set that both numbers divide into exactly.
Step-by-step explanation:
When considering the divisibility relation on the set {1, 2, 3, 6, 8, 12, 24, 36}, the least upper bound of elements 8 and 12 is the smallest number in the set that both 8 and 12 divide into without leaving a remainder. In this set, 24 is the least upper bound (also known as the least common multiple) for 8 and 12, because 24 is divisible by both 8 (24 ÷ 8 = 3) and 12 (24 ÷ 12 = 2), and there is no smaller number in the set that satisfies this condition.