If you’re using TSQL ISNUMERIC function in a query, e.g.

select * from MYTABLE WHERE ISNUMERIC(MYSTRING) = 1

You may receive unexpected error:

String or binary data would be truncated.

ISNUMERIC must truncate string data, and if you experienced the above error, some of your data is over the limit. But you can augment the above query:

select * from MYTABLE WHERE ISNUMERIC(LEFT(MYSTRING, 8000)) = 1

But cutting only 8000 chars you will avoid the error, and I seriously doubt you will have number over 8000 digits long so it’s a safe bet as well