// instead of  String  you can use  char*
#include <LiquidCrystal.h>
LiquidCrystal lcd(12,11,10,9,8,7);
int button = 3;
int m = false;
int x;

void setup() {
  // put your setup code here, to run once:
  lcd.begin(16,2);
  pinMode(button, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
  int buttonState = digitalRead(button);
  if(buttonState == LOW & m == false){
    lcd.setCursor(0,6);
    m = !m;
    x=random((0,6));
    delay(1);
  }
  buttonState = digitalRead(button);
  if(buttonState == HIGH & m == true){
    m = !m;
    lcd.clear();
    delay(1);
  }
  lcd.setCursor(7,0);
  lcd.print(x);
}