Question

The sum of the first 88 terms of the sequence 8+18+28+... is?

Answer 1

This is some sequence. Let me see if I can figure it out.

So your tens digit will always be n-1, meaning your first term is 1-1 so your tens digit is 0, and the number is 8, your second term is 2-1 so your second tens digit is 1 and the number is 18.

You can say that you have (n-1) "tens" or 88 tens. Since the sequence is linear, you can say that the sum of the largest "ten" and the smallest "ten" is the the sum of the next largest "ten" and the next smallest "ten" and so on. When paired, you have 44 of these "tens." So your largest is 870+0, the next largest and smallest terms are 860+10, the next 850+20. The average is 435 x 44 = 19140.

You also have an 88 "8s" in the ones digit. 88x8 = 704.

704+19140 = 19844.