Solve the Multiplication Equation: Finding the Number That Makes ?×10=45

To solve the problem $? \times 10 = 45$, we can use the following steps:

• Step 1: Understand the equation $(? \times 10 = 45)$.
• Step 2: Rearrange the equation to solve for the unknown: $? = \frac{45}{10}$.
• Step 3: Perform the division operation: $\frac{45}{10} = 4.5$.

We divide 45 by 10 to find that the missing number is 4.5. Therefore, $4.5 \times 10 = 45$.

Thus, the missing number in the equation is $\boxed{4.5}$.

From the given choices, the correct answer is $\boxed{4.5}$, which corresponds to choice 3.