Extract numbers from text string

I am trying to write a formula to extract the number from a cell with a text string (containing the number). Besides not knowing how to do this, the complication is that the numbers are not always 4-digits and I don't want the "-n" part of the number. I appreciate anyones help. The attached file "Test1" has example data in sheet 1. The data is in column B and the desired result is in column C.