Solve the Multiplication Equation: Finding the Number in ? × 4 = 0

First, we examine the equation $? \times 4 = 0$. The Zero Product Property tells us that for any number multiplied by another to result in zero, at least one of the numbers must be zero.

Since the right side of the equation is zero, $?$ must be zero because any real number multiplied by zero results in zero, regardless of the other factor.
Therefore, we can conclude:

The solution to the problem is $\boxed{0}$.