LCDs measuring volts arduino How do we measure 100 Volts Arduino LCD Proje

#include &lt;LiquidCrystal.h&gt;
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
int analogInput = 0;
float vout = 0.0;
float vin = 0.0;
float R1 = 100000.0; // 100K ohm direnç
float R2 = 10000.0; // 10K ohm direnç
int value = 0;
void setup(){
   pinMode(analogInput, INPUT);
   lcd.begin(16, 2);
   lcd.print("DC VOLTMETRE-PROJEHOCAM");
}
void loop(){
   // read the value at analog input
   value = analogRead(analogInput);
   vout = (value * 5.0) / 1024.0; 
   vin = vout / (R2/(R1+R2)); 
   if (vin&lt;0.09) {
   vin=0.0;
} 
lcd.setCursor(0, 1);
lcd.print("VOLTAJ V= ");
lcd.print(vin);
delay(500);
}
The project that you show as your reference : link in your question,  shows this picture :  

  

Change R1 to 200 K ohms.   The Arduino will receive 4.76 volts when the input is 100 volts.   

You will also need to change your program line for float R1 = 100000.0;

CAUTION :  Beware of high voltage.  Also, the Arduino is not isolated from the 100 volts.