how to calculate number ranges

[Lori]

I am trying to calculate how many total numbers appear in a range of numbers.
The first 2 columns would have the beginning and end numbers for the range.
If there is only 1 number for the range it would appear in the first column
and the second column would be blank. (When I use the formula B1-A1+1 I get
a negative number in third column instead of a 1.)

Any help would be greatly appreciated.

1500 1504 5
1505 1
1506 1508 3
1509 1
1512 1515 4
1516 1

 

[N Harkawat]

=IF(B1="",1,B1-A1+1)*ISNUMBER(A1)

 

[Lori]

Thank you. This is exactly what I needed.

=IF(B1="",1,B1-A1+1)*ISNUMBER(A1)