1. The bending force, P, can be calculated using the formula P = K * B * t * σb, where P represents the bending force acting on a sheet, B is the width of the workpiece in millimeters, σb is the ultimate tensile strength of the material, t is the thickness of the workpiece in millimeters, and K is the bending coefficient, also known as the K factor.2. The coefficient K factor is a term used to describe the bending coefficient, which is influenced by the material's properties and thickness. Different materials or sheets with varying thicknesses will have different coefficients.