Exports from other systems often arrive as text that only looks like numbers. The signs: values sit on the left, SUM returns 0, and a lookup can't find them.
Formulas convert them into a new column:
=VALUE(B2) reads text such as "$1,240.50" or " 1042 " as a number. =--B2 (two minus signs) does the same in less typing.=DATEVALUE(D2) reads a date written as text, such as "2026-03-02", and returns the date's serial number; format the column as a date.- Some accounting systems put the minus at the end: "120-". Remove it with SUBSTITUTE and negate:
=-VALUE(SUBSTITUTE(F2,"-","")).
When the new column is right, you can copy it and paste it over the original as values.