The conversation between human and AI assistant.
What is the answer of 5+10+15...+100?
How did you calculate that?
The formula for the sum of an arithmetic sequence is n/2(a+l), where n is the number of terms, a is the first term, and l is the last term. In this case, there are 20 terms, the first term is 5, and the last term is 100. Therefore, the sum is 20/2(5+100) = 1050.