Arduino Based Digital Calculator

#include <LiquidCrystal_I2C.h>
#include <Keypad.h>

LiquidCrystal_I2C lcd (0x27, 16, 2);

const byte rows = 4;
const byte cols = 4;

char hexKeys [rows][cols] = {

  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[rows] = {4, 5, 6, 7};
byte colPins[cols] = {0, 1, 2, 3};

Keypad kpd = Keypad (makeKeymap(hexKeys), rowPins, colPins, rows, cols);

long number = 0;

char dynamicKeys;
String string = "";

boolean enterkey_state;
boolean binButton_state;
boolean hexButton_state;
boolean octButton_state;
boolean decButton_state;

void setup()
{
  lcd.begin();
  lcd.backlight();

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Initializing");
  for (int i = 12; i <= 16; i++)
  {
    delay(200);
    lcd.print("*");
  }
  delay(3000);
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Digital");
  lcd.setCursor(0, 1);
  lcd.print("Calculator");

  delay(3000);
  lcd.clear();
}

void loop()
{
  enterkey_state = false;
  binButton_state = false;
  hexButton_state = false;
  octButton_state = false;
  decButton_state = false;
  
  dynamicKeys = kpd.getKey();

  if (dynamicKeys)
  {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("|>");
    string = string + dynamicKeys;
    lcd.print(string);
    number = string.toInt();
  }

  if (dynamicKeys == 'A')
  {
    octButton_state = true;
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("OctaDecimal");
    lcd.setCursor(0, 1);
    lcd.print("|>");
    lcd.print(number, OCT);
  }
  else if (dynamicKeys == 'B')
  {
    binButton_state = true;
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Binary");
    lcd.setCursor(0, 1);
    lcd.print("|>");
    lcd.print(number, BIN);
  }
  else if (dynamicKeys == 'C')
  {
    hexButton_state = true;
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("HexaDecimal");
    lcd.setCursor(0, 1);
    lcd.print("|>");
    lcd.print(number, HEX);
  }
  else if (dynamicKeys == 'D')
  {
    decButton_state = true;
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Decimal");
    lcd.setCursor(0, 1);
    lcd.print("|>");
    lcd.print(number, DEC);
  }
  else if (dynamicKeys == '#')
  {
    enterkey_state = true;
    
    lcd.clear();
    lcd.print("Entered Number");
    lcd.setCursor(0, 1);
    lcd.print("|>");
    lcd.print(number);
  }
  else if (dynamicKeys == '*')
  {
    number = 0;
    string = "";
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Enter Number");
    lcd.setCursor(0, 1);
    lcd.print("|>");
  }
}