Simulation of Calculator Keypad with Arduino in Proteus

#include <Keypad.h>

const byte ROWS = 4; //four rows
const byte COLS = 4; //three columns
char keys[ROWS][COLS] = {
{'7','8','9', '/'},
{'4','5','6','x'},
{'1','2','3','-'},
{'*','0','#','+'}
};
byte rowPins[ROWS] = {13, 12, 11, 10}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {9, 8, 7, 6}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

int KeyCheck = 0;

void setup()
{
Serial.begin(9600);

}

void loop()
{
char key = keypad.getKey();

if (key)
{
if(key == '1'){KeyCheck = 1; Serial.print("1");}
if(key == '2'){KeyCheck = 1; Serial.print("2");}
if(key == '3'){KeyCheck = 1; Serial.print("3");}

if(key == '4'){KeyCheck = 1; Serial.print("4");}
if(key == '5'){KeyCheck = 1; Serial.print("5");}
if(key == '6'){KeyCheck = 1; Serial.print("6");}

if(KeyCheck == 0){Serial.print(key);}
KeyCheck = 0;
}

}