how to save excel columns with long numbers into csv?
Append a TAB char (ASCII 9) at the end of a number.
In order to have those long (>15 digit) numbers in Excel, they are already formatted as text. I suspect that the .csv file also shows them as long numbers (if you open the csv file with Notepad), but that when you open the csv file in Excel, you see them as truncated and converted to scientific notation.
If that is the case, what you need to do is IMPORT the csv file. When you do that, the text-to-columns wizard will open, and allow you to format that column as text. The location of the Import is different in different versions. In Excel 2007, it is on the Data ribbon, Get External Data / From Text.
If, as the original question seems to imply, you are actually:
- already working with data in Excel, and
- want to save to a CSV format without losing digits in an extra long number,
Then, before doing a 'Save As' to your CSV format, try formatting the column with a custom format, and in the box for the pattern just type #. This will force Excel to see it as a number, however many digits long, without trying to do something else with it like 4.52364E+14 when you actually save it to CSV.
At least, that is how it works for me in Excel 365 at this point in time.
If you are trying to get data into Excel from a CSV, then the answer about using the data import wizard is probably the safest bet instead.
put the number as a function like below: ="123456789123456789"