Density is defined as the mass (grams) per unit volume (in this case, milliliters) of a substance.
A balance could be used to find mass of the piece of silver.
The piece of silver is most likely not a uniform shape (such as a perfect square or rectangle). Therefore, multiplying its mass, height, and width would not be a valid approach in determining its volume. Instead, water displacement would be used to find the volume of the silver.
During water displacement, an initial volume of water is poured into a graduated cylinder. This volume is recorded. Then, the irregularly shaped object (in this case, the piece of silver) is gently slid into the graduated cylinder (so as not to splash any water on the sides of the cylinder, which would lead to percent error). The volume of the water in the graduated cylinder will rise (is displaced) once the object is added to the cylinder. This new volume is also recorded. The volume of the object is the new volume minus the initial volume.
Once the mass and volume of the silver is determined, the density of the silver can be calculated by dividing the mass by the volume.