Imported CSV file into Excel but cannot convert the numerals from TEXT to a usable number format in order to calculate sums

Two possible causes:

a) Decimal point versus decimal comma
   (i.e. numbers are treated as being text, as they do not match "the number format")
   Use Search and replace to rectify it.

b) Cell content stored as Text

• First make sure none of the cells contains a ' as first character, these need to be removed if there are any. (The ' tells Excel to treat the content as being Text, unconditionally)
• Select the cells, then hold CTRL and hit 1, make sure to set "General" or "Number" as format, click OK.
• Then use a free cell, make sure it is not in Text format as above and enter a single 1 in that cell.
• Place the cursor on that cell, hold CTRL and hit C.
• Now select the offending numeric cells again.
• Then use "Paste special" (In the Ribbon for later Excel versions) and select "Multiply", click OK.

The numbers should now act as being numbers when used in formulas.

Load the CSV in a new tab, which you may have done already.

On the sheet that performs the calculations, create a reference to the cells to be calculated but add INT() function to it.

For example:

=INT(MyCSV_data!B2)

This forces the text to become an integer value.