Count total number of digits from 1 to n | Java program to count total number of digits we have to write from 1 to n ; number_of_digits store total digits we have to write ; In the loop we are decreasing 0 , 9 , 99 ... from n till ( n - i + 1 ) is greater than 0 and sum them to number_of_digits to get the required sum ; Driver Method
public class GFG { static int totalDigits ( int n ) { int number_of_digits = 0 ; for ( int i = 1 ; i <= n ; i *= 10 ) number_of_digits += ( n - i + 1 ) ; return number_of_digits ; } public static void main ( String [ ] args ) { int n = 13 ; System . out . println ( totalDigits ( n ) ) ; } }