1. **State the problem:** We need to express "four added to a number" as an algebraic expression. 2. **Identify the variable:** Let the number be represented by $x$. 3. **Form the expression:** Adding four to the number means we add 4 to $x$. 4. **Write the expression:** The algebraic expression is $$x + 4$$. This expression represents four added to a number $x$.