SUM positives or negatives only
By Neale Blackwood, 30 Apr 15
If you need to SUM only the positive numbers in a range then use the SUMIF function. If the range is A1:A1000 then the following formula will SUM only the positive numbers.
This following formula will SUM all the negative amounts
The third part of a SUMIF function is optional and can be omitted if the range you want to SUM is the same as the Criteria range, as in the two examples above.