To determine the scale of a 16 cm airplane model, you need to know the length of the actual airplane (real-world size). The scale is the ratio of the model’s size to the actual size.
Formula for Scale:
Scale=Model LengthActual Airplane Lengthtext{Scale} = frac{text{Model Length}}{text{Actual Airplane Length}}Scale=Actual Airplane LengthModel Length​
Steps to Calculate:

Find the actual length of the airplane in the real world (in the same units as the model). For example, if the airplane is 40 meters long (4,000 cm), convert it to centimeters.
Divide the model length (16 cm) by the real-world length.

Example:
If the real airplane is 40 meters long (4,000 cm):

Scale=Model Length (16 cm)Actual Length (4,000 cm)=164000=1:250text{Scale} = frac{text{Model Length (16 cm)}}{text{Actual Length (4,000 cm)}} = frac{16}{4000} = 1:250Scale=Actual Length (4,000 cm)Model Length (16 cm)​=400016​=1:250

So, the scale of the model is 1:250.