 
 byte displayNum[] = {off, off, off, off};  //array for display numbers from msb to lsb
 
-bool negative = false;
-
 const long refreshInterval = 10; //refresh delay in microseconds
 long previousRefresh = 0; //previous refresh time
 int refreshLoop = 0;  //counter for refreshing loop

    displayNumber();
  }

  //testCaseAllNum();
  splitNumber(1000);
}

void clearLEDs() {

void displayNumber() {
  //turn on the LEDs accoring to the number stored in array num on the refresh cycle
  updateShiftRegister(displayNum[refreshLoop]);
}

void updateShiftRegister(byte leds) {
