function in excel for returning a negative value
3. Click the lower right corner of cell C1 and drag the formula down. Result: 4. To change the negative numbers to zero but leave the positive numbers unchanged, instead of =A1-B1, use =MAX(0,A1-B1) and drag the function down. Result: Explanation: the MAX function returns the maximum of two values. If the result of the formula is negative, the function returns 0.