Presently troubleshooting a problem where running this SQL query:
UPDATE tblBenchmarkData SET OriginalValue = DataValue, OriginalUnitID = DataUnitID, D
It would be helpful to see the schema definition of tblBenchmarkData, but you could try using ISNUMERIC in your query. Something like:
SET DataValue = CASE WHEN ISNUMERIC(DataValue)=1 THEN CAST(DataValue AS float) * 1.335 ELSE 0 END