Try also the SQL2005 documentation :
1) Learn more about string (char, varchar, ...) concatenation
+ (String Concatenation) (Transact-SQL)
2) Learn more about arithmetic operator :
* (Multiply) (Transact-SQL)
Multiplying by 10 in the decimal world is just as multiply by 2 (decimal) or 10 (binary) in the binary world : just shift all digits 1 position left and put the 0 in the most right open position. After that you add 1 to the numeric value and the 0 in most right position will become a 1.
Just what u want, or not ?
if not give us an example that not match !!