Explanation
Consider the set {1,2,3,...,18,19,20}
We could count the values in that set and find there are 20 of them.
As a shortcut, we can subtract the endpoints to get 20-1 = 19. We then add on 1 because the subtraction ignores the first element. So there are really 20-1+1 = 20 items in the set as expected.
The formula is: b-a+1 where a,b are the endpoints and b > a
Let's consider the set {4,5,6}. Clearly there are 3 items here and notice that b-a+1 = 6-4+1 = 3.
As another example, there are 10 items in the set {9,10,11,...17,18} since b-a+1 = 18-9+1 = 10.
Onto your current question we have a = 176 and b = 389, so,
b-a+1 = 389-176+1 = 214
There are 214 integers in the set {176,177,178,...,388,389}.
In other words, there are 214 integers between 176 and 389 where we include both endpoints.
