Meaning of: "If you're wanting to store a number and you store it as a string, it actually takes up more space on disk."

Different data types take up different amounts of storage. For example, a 10-digit number less than about 4.3 billion can be stored in 32 bits, or 4 bytes of memory. This is because all 32 bits are used to represent the number in binary. But if this same name number were stored as a string, each digit would be represented by a code that uses an entire byte, plus there may be another byte of overhead, so that's 11 bytes.

The exact space taken up by each data type varies a bit depending on which type of database, and would be described in that database's technical specifications. These concerns are not significant except for very large amounts of data, and the optimization of storage and procedures is a very advanced topic area.

There's a bunch of web pages with info on this. One I've found interesting for MySQL is http://www.developwebsites.net/choose-optimal-mysql-data-type/.

This is for MySQL, and I believe the Workspaces are SQLite, but I doubt it's much different. If I read it correctly INTs require 4 bytes, and VARCHARs require 1 byte per character + 1 byte. So 123 would require 4 bytes as an INT, 4 bytes as a VARCHAR, but 1234567 would require 4 bytes as an INT, 8 bytes as a VARCHAR, or twice as much. So as the numbers get larger the difference gets worse. Of course, here we are talking about databases. I've looked at some sites that talk about the memory requirements of objects in java, and again, if reading correctly, String objects are quite a bit bigger that ints.