How do you search an entier spreadsheet and do the following:

1) Check if the contents of a cell is numeric?
2) If content is numeric then search for blanks (" ") and replace them with
nothing (""). E.g. I hace a number in a cell written like: 1000 22 458 but
want to convert it to 100022458. I do not want text like: 'Market value' to
be replaced by 'Marketvalue'.

Please help me on this one!!!
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I am very thankful for any fast assistance!