There is such a thing called data types in programming. Different data types describe different things.
For example one data type could represent integers, just like 5 or 10.
There is also another data type that represents text, like "5", "10", or "hey blargeg blahness", this data type is usually called a string in most languages.
Python doesn't know that the raw input are numbers, hence the * operator is invalid.
So what you must do, is something called casting. It's the conversion of one data type to another. In order to cast one data type to another you must use the syntax:
datatype1(variable containing datatype2)
Example:
int("5")
In python, an integer is called an int, and a number (which can contain decimals) is called a float (google floating point).
So you can accommodate for the user entering decimals by using float instead of int.
width = float(raw_input ("Please type the width of the object." ));
Hope this helps :)