#include <LiquidCrystal_I2C.h>
#include <math.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4

#define e 2.7182818284590452353602874713527

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

void setup() {
  lcd.begin(16, 2);
  lcd.backlight();
}

void loop() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("e: ");
  lcd.print(e, 7); 
  delay(10000);
}