help!! i need to make some Calculator from adruino

i need to make + - * / in my arduino
my code can use on tinkercard can running but can’t use on arduino
sorry my english bad
this my code

#include <math.h>
#include <stdio.h>

int buttonState = 0;

int lesAvPC() { //vil ha float her - This is where I want float
  while (Serial.available() == 0); 

  return Serial.parseInt(); 
}

void setup() {
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(4, INPUT);
  pinMode(5, INPUT);
  pinMode(13, OUTPUT);
  Serial.begin(9600);
  Serial.println("=================================");
  Serial.println("Test Serial by stdio.h"); 
  Serial.println("Lab6");
  Serial.println("Arithmetic(+,-,*,/"); 
  Serial.println("=================================");
  Serial.println("=============================");
  Serial.println("Select Arithmetic Menu");
  Serial.println("1.Plus(+)");
  Serial.println("2.Minus(-)");
  Serial.println("3.Multiply(*)");
  Serial.println("4.Divide(/)");
  Serial.println("==================================");
  Serial.println("Please push the button for select menu");
  

}




void loop() { 
  
  buttonState = digitalRead(2);
  if (buttonState == HIGH) {
   
    Serial.print("1.Input Enter First value: "); 
        float num1 = lesAvPC();
        Serial.println(num1);
        Serial.println("   Operand:  +"); 
        Serial.print(" Input Enter Second value: "); 
        float num2 = lesAvPC();
        Serial.println(num2);
        Serial.println(" ");
        Serial.print("      Answer: "); 
        float fasit = num1 + num2;
        Serial.println(fasit); 
        Serial.println(" ");
        Serial.println("........................................"); 
        
  }       
 
  
  buttonState = digitalRead(3);
  if (buttonState == HIGH) {
   
    Serial.print("2.Input Enter First value: ");
        float num1 = lesAvPC();
        Serial.println(num1);
        Serial.println("   Operand:  -"); 
        Serial.print(" Input Enter Second value: ");
        float num2 = lesAvPC();
        Serial.println(num2);
        Serial.println(" ");
        Serial.print("     Answer: ");
        float fasit = num1 - num2;
        Serial.println(fasit);
        Serial.println(" ");      
        Serial.println("........................................"); 
        
  }
  
  buttonState = digitalRead(4);
  if (buttonState == HIGH) {
   
    Serial.print("3.Input Enter First value: ");
        float num1 = lesAvPC();
        Serial.println(num1);
        Serial.println("   Operand:  *"); 
        Serial.print("    Input Enter Second value: ");
        float num2 = lesAvPC();
        Serial.println(num2);
        Serial.println(" ");
        Serial.print("           Answer: ");
        float fasit = num1 * num2;
        Serial.println(fasit);
        Serial.println(" ");        
        Serial.println("........................................"); 
        
  }
  
  buttonState = digitalRead(5);
  if (buttonState == HIGH) {
   
    Serial.print("4.Input Enter First value: ");
        float num1 = lesAvPC();
        Serial.println(num1);
        Serial.println("   Operand:  /"); 
        Serial.print("    Input Enter Second value: ");
        float num2 = lesAvPC();
        Serial.println(num2);
        Serial.println(" ");
        Serial.print("           Answer: ");
        float fasit = num1 / num2;
        Serial.println(fasit);
        Serial.println(" ");      
        Serial.println("........................................"); 
        
  }
   

  
}

i must use switch case,push button,serial

please help thank you

How are your buttons wired?

Research the correct use of INPUT_PULLUP.

but can't use on arduino

Why not? What happens? How does that compare to what you expected? We can’t help much if you don’t tell us what’s wrong.