Convert negative numbers into positive ones

I need a quick solution to convert all the negative numbers in my sheet to positive ones. There are positive numbers but I just want a formula to convert all the negatives to positives. I don't want to just replace the minus sign with the 'replace' tool as I need the numbers to go into a pivot table and when I did this earlier the pivot table still considers them negative.

Thanks

That's exactly what I don't want...

What's the ABS function and what's the formula?