The problem asks to convert $15$ centimeters and $4$ millimeters to millimeters.

1. Problem Description

The problem asks to convert $15$ centimeters and $4$ millimeters to millimeters.

2. Solution Steps

We need to convert $15$ centimeters to millimeters and then add the remaining $4$ millimeters. We know the conversion factor between centimeters and millimeters:

$1 \text{ cm} = 10 \text{ mm}$

Therefore, $15$ centimeters is equal to $15 \times 10$ millimeters.

$15 \text{ cm} = 15 \times 10 \text{ mm} = 150 \text{ mm}$

Now we add the remaining $4$ millimeters to the converted value:

$150 \text{ mm} + 4 \text{ mm} = 154 \text{ mm}$

3. Final Answer

$154$