fix DEFAULT_AXIS_STEPS_PER_UNIT minor Z rounding error

Marlin/Configuration.h

@@ -282,7 +282,7 @@ const bool Z_ENDSTOPS_INVERTING = true; // set to true to invert the logic of th
 
 // default settings 
 
-#define DEFAULT_AXIS_STEPS_PER_UNIT   {78.7402,78.7402,200*8/3,760*1.1}  // default steps per unit for ultimaker 
+#define DEFAULT_AXIS_STEPS_PER_UNIT   {78.7402,78.7402,200.0*8/3,760*1.1}  // default steps per unit for ultimaker
 #define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 25}    // (mm/sec)
 #define DEFAULT_MAX_ACCELERATION      {9000,9000,100,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.