1. The problem statement, all variables and given/known data Hello! Binary search requires O( log2(n) ) operations in the worst case. My math doesn't add up. I would be grateful for help. 2. Relevant equations For example: Find number 8 in the set 1234578. 3. The attempt at a solution The set contains n = 7 elements. 1) take the middle number 4; 4 < 8 2) take the middle number in the right half of the set 7; 7 < 8 3) in the next right half we have only 1 element and it's 8. done. Thus I've made 3 operations to find the element 8. 2 to the power 3 equals 8, but there are only 7 elements in the set. Hence, O(log2(n) - 1) operations. I don't see why it is log2(n). Thank you!