#include <LiquidCrystal.h>
  //Header file for LCD from https://www.arduino.cc/en/Reference/LiquidCrystal
#include <Keypad.h> //Header file for Keypad from https://github.com/Chris--A/Keypad

const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns

// Define the Keymap
char keys[ROWS][COLS] = {

  {'1','2','3','A'},

  {'4','5','6','B'},

  {'7','8','9','C'},

  {'*','0','#','D'}

};

byte rowPins[ROWS]
  = { 0, 1, 2, 3 };// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these Arduino pins.
byte
  colPins[COLS] = { 4, 5, 6, 7 }; // Connect keypad COL0, COL1 and COL2 to these Arduino pins.

Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS); //  Create the Keypad

const int rs = 8, en = 9, d4 = 10, d5 = 11, d6 =12, d7 = 13; //Pins to which LCD is connected
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

 long Num1,Number;
 char key,action;
 boolean result = false;
 
void setup() {
  lcd.begin(16, 2); //We are using a 16*2 LCD display
  lcd.print("Print Cost Calc"); //Display a intro message
  lcd.setCursor(0,
1);   // set the cursor to column 0, line 1
  lcd.print("Type Print Mass");//Display a intro message 

   delay(2000); //Wait for display to show info

    lcd.clear(); //Then clean it
}

void loop() {
  
key = kpd.getKey(); //storing pressed key value in a char

if (key!=NO_KEY)
DetectButtons();

if (result==true)
CalculateResult();

DisplayResult();   
}

void
  DetectButtons()
{ 
    
    lcd.clear(); //Then clean it
    if (key=='*') //If cancel Button is pressed
    {Serial.println ("Button Cancel"); Number=Num1=0; result=false;}
    
    lcd.setCursor(1,0);   // set the cursor to column 0, line 1
    lcd.print("Type Print Mass");//Display a intro message 

     if (key == '1') //If Button 1 is pressed
    {Serial.println("Button 1"); 
    if (Number==0)
    Number=1;
    else
    Number = (Number*10) + 1; //Pressed twice
    }
    
     if (key == '4') //If Button 4 is pressed
    {Serial.println ("Button 4"); 
    if (Number==0)
    Number=4;
    else
    Number = (Number*10) + 4; //Pressed twice
    }

    
     if (key == '7') //If Button 7 is pressed
    {Serial.println ("Button 7");
    if (Number==0)
    Number=7;
    else
    Number = (Number*10)+ 7; //Pressed twice
    } 
  

    if (key == '0')
    {Serial.println("Button 0"); //Button 0 is Pressed
    if (Number==0)
    Number=0;
    else
    Number = (Number*10) + 0; //Pressed twice
    }
    
     if (key == '2') //Button 2 is Pressed
    {Serial.println ("Button 2"); 
     if (Number==0)
    Number=2;
    else
    Number = (Number*10) + 2; //Pressed twice
    }
    
     if (key == '5')
    {Serial.println ("Button 5"); 
     if (Number==0)
    Number=5;
    else
    Number = (Number*10)+ 5; //Pressed twice
    }
    
     if (key == '8')
    {Serial.println("Button 8"); 
     if (Number==0)
    Number=8;
    else
    Number = (Number*10) + 8; //Pressed twice
    }   
    
     if (key == '3')
    {Serial.println ("Button 3"); 
     if (Number==0)
    Number=3;
    else
    Number = (Number*10) + 3;//Pressed twice
    }
    
     if (key == '6')
    {Serial.println("Button 6"); 
    if (Number==0)
    Number=6;
    else
    Number = (Number*10) + 6; //Pressed twice
    }
    
     if (key == '9')
    {Serial.println ("Button 9");
    if (Number==0)
    Number=9;
    else
    Number = (Number*10) + 9; //Pressed twice
    }  

      if (key == '#') //Detecting Buttons on Column 4

  {
    Num1 = Number;    
    Number =0;
    if (key == '#')
    {Serial.println("Calculate"); action = '$';} 
    delay(100);
  }
  
}

void CalculateResult()
{

  if (action=='$')
    Number = 1+(0.25*((Num1-20)/10));
}

void DisplayResult()
{
  lcd.setCursor(0,0);   // set the cursor to column 0, line 1
  lcd.print(Num1); lcd.print(action);
  
  if (result==true)
  {lcd.print("="); lcd.print(Number);}//Display the result
  
  lcd.setCursor(0, 1);   // set the cursor to column 0, line 1
  lcd.print(Number); //Display the result
}