What is the arithmetic mean of the integers from 16 to 20, inclusive?

The mean of sequential integers is the middle number, namely 18.

Alternatively, we can calculate the mean

(16+17+18+19+20) / 5=90/5=18.

We can also think of the mean as

(18-2+18-1+18+18+1+18+2) / 5=5*18/5=18