Changing numbers entered as text into numbers

I have an Excel table with 4 000 rows. The data in the columns are numbers but they have been entered as text (from another database). How do I turn a column with 4 000 rows from text format into numbers format so that I can sort the numbers?

Just select all and click convert to numbers from Error Checking Drop down

there is a quick fix...

a. put the number 1 in any empty cell other then the column with textnumbers
b. do CTRL+C to copy that cell content
c. select your column(s) with the 4000 textnumbers
d. Choose pastespecial and then in the menu select multiply and press OK

now your numbers will go from text to values again

Pls see attached Pic

I am sorry, it apperas my question was inaccurate. It appears that what looked like numbers (eg 10.60) are actually stored in the Excel column as years in this format. The original number is 10,60. How do I get from the year format back to the original numbers?

Here is a sample of the database. When the data was transferred from a database to Excel all the numbers were stored as years in this format. These are boatlengths and I need to sort them so they need to be converted to numbers.

As AliGW said it is your locale.
Highlight entire range and use Find/Replace "." point with "," comma
Then see what you format tells you.

Following the advice of ibuhary to use the Error Checking drop down Excel informs me that the data is stored as a "two-digit year in a text format date", which I have difficulties understanding. In any case, the choices then available to me from the Error Checkin are to store the number in 19XX or 20XX format, both of which yield a 5-digit number which is of no use to me. The data is coming from a Swedish-speaking locale. I am not able to access the orginal data.

Can you tell us what kind of data is in these cells, then we could guide you accordingly.

If they are dates, then you need to understand that in Excel dates are stores as "5 Digit Numbers" and its just the format of the cells that will change the way its displayed to the user.

E.g. 43514 is today's date in excel and it can be displayed in many ways including some mentioned below:
Year only as "2019"
Month only as "02"
Day only as "18"
Weekday only as "2" or "Monday"
Whole date as "02/18/2019" or "18-Feb-2019"

So once you convert your text to numbers you need to play further in the format of the cells to get it display what you need.

In case you need any further clarifications pls do not hesitate to buzz....

Thank you all, torachans solution solved the problem, simple and elegant!