// this code and design is in the public domain
// designed by Peterthinks Sept 25th 2021
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,20,3);   

long  sensorValue1 = 0;
float FsensorValue1 = 0;
int   sensorValue2 = 0;
long  sensorValue3 = 0;
float FsensorValue3 = 0; 

void setup()
{
  lcd.begin(16, 2); 
  lcd.backlight();
  pinMode(A1, INPUT); 
  pinMode(A2, INPUT); 
  pinMode(A3, INPUT); 
}

void loop()
{
  sensorValue1 = analogRead(A1);
  sensorValue2 = analogRead(A2);
  sensorValue3 = analogRead(A3);
  FsensorValue1 = analogRead(A1);
  FsensorValue3 = analogRead(A3);
  sensorValue1 = map(analogRead (A1), 0, 1023, 0, 100);
  sensorValue3 = map(analogRead (A3), 0, 1023, 0, 100);
  FsensorValue1 = map(analogRead (A1), 0, 1023, 0, 100);
  FsensorValue3 = map(analogRead (A3), 0, 1023, 0, 100);  

  if (sensorValue2 <= 256)
  { 
  lcd.setCursor(0, 0);
  lcd.print(sensorValue1);
  lcd.print(" + ");
  lcd.print(sensorValue3);
  lcd.print("                ");
  lcd.setCursor(0, 1);
  lcd.print(sensorValue1+sensorValue3);
  lcd.print("                "); 
  }

  else if (sensorValue2 > 256 && sensorValue2 <= 512)
  {   
  lcd.setCursor(0, 0);  
  lcd.print(sensorValue1);
  lcd.print(" - ");
  lcd.print(sensorValue3);
  lcd.print("                ");
  lcd.setCursor(0, 1);  
  lcd.print(sensorValue1-sensorValue3);
  lcd.print("                "); 
  }
 
  else if (sensorValue2 > 512 && sensorValue2 <= 768)
  {
  lcd.setCursor(0, 0); 
  lcd.print(sensorValue1);
  lcd.print(" * ");
  lcd.print(sensorValue3);
  lcd.print("                ");   
  lcd.setCursor(0, 1);   
  lcd.print(sensorValue1*sensorValue3);
  lcd.print("                ");   
  }

  else
  {

  lcd.setCursor(0, 0); 
  lcd.print(sensorValue1);
  lcd.print(" / ");  
  lcd.print(sensorValue3);
  lcd.print("                ");  
  lcd.setCursor(0, 1);
  lcd.print(FsensorValue1/FsensorValue3,4);
  lcd.print ("                ");
  } 
}