Fix the very core multiply function
Fix the very core multiply function

alexrj/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,curieos/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,alexrj/Slic3r,alexrj/Slic3r,pieis2pi/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,alexrj/Slic3r,curieos/Slic3r