To convert centimeters to inches, we use the conversion factor that 1 inch is equal to 2.54 centimeters. To find the number of inches in 12.8 centimeters, we set up the equation: 12.8 cm * (1 inch / 2.54 cm) = x inches. By simplifying this, we divide 12.8 by 2.54, which gives us approximately 5.039 inches. This conversion is essential in various fields, including science and engineering, where different measurement systems are used.