Depends, you could get 72, 80, 81, or 90. But probably not 100.
Simple way to find out: try it!
int n = 10;
int count = 0;
for (int i = 1; i < n; i++)
for (int j = 1; j < n - 1; j++)
count++;
Console.WriteLine(count);
count = 0;
for (int i = 1; i <= n; i++)
for (int j = 1; j < n - 1; j++)
count++;
Console.WriteLine(count);
count = 0;
for (int i = 1; i < n; i++)
for (int j = 1; j <= n - 1; j++)
count++;
Console.WriteLine(count);
count = 0;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n - 1; j++)
count++;
Console.WriteLine(count);
Myself? Given that one of your loops is specific about "inclusive" and the other isn't I'd go with 81 ...