Imported amounts can look numeric while Excel stores them as text. The mismatch can produce unexpected calculations or sorting. Before converting anything, decide whether the column represents quantities to calculate or labels whose exact characters must stay intact.

Keep identifiers, account codes and telephone numbers out of a blanket conversion. Leading zeros may be meaningful there. Make a copy of the workbook and choose a small sample of the amount column, including a negative value and a decimal where present.

Convert the data, then inspect the result

In desktop Excel, cells recognised as numbers stored as text may display an error indicator. Select the relevant cells and use Convert to Number from that indicator. The warning is a useful clue, but it may be disabled, so its absence does not establish the cell type.

Microsoft also documents a helper-column method. Beside the imported text, enter a formula such as =VALUE(C2) and fill it down the intended rows. Keeping the original column alongside the converted results makes inspection easier.

If VALUE produces an error, investigate the source text and its number convention. Do not replace the error with zero merely to make a total finish calculating. That would convert an unresolved interpretation problem into a plausible but incorrect amount.

Reconcile before replacing the source column

Compare the sample results with the original document or export. Confirm decimal separators, negative signs and the number of populated records. Check a subtotal against an independently known result when one is available.

Only after that check, decide whether to retain the helper column or copy its results back using Paste Special, Values. Preserve the untouched import separately if it is the evidence for the calculation.

Finally, repeat the calculation or sort that originally behaved unexpectedly. A disappearing warning triangle is not the entire goal: the intended amounts must now work correctly while neighbouring identifiers retain their original characters.

References: Microsoft: converting numbers stored as text.