Sum of integers upto N with given unit digit ( Set 2 ) | Java implementation of the approach ; Function to return the required sum ; Decrement N ; Driver code
import java . io . * ; class GFG { static long getSum ( long n , int d ) { if ( n < d ) return 0 ; while ( n % 10 != d ) n -- ; long k = n / 10 ; return ( k + 1 ) * d + ( k * 10 + 10 * k * k ) / 2 ; } public static void main ( String [ ] args ) { long n = 30 ; int d = 3 ; System . out . println ( getSum ( n , d ) ) ; } }