Sum of last digit of all integers from 1 to N divisible by M | Java implementation of the approach ; Function to return the required sum ; Number of element between 1 to n divisible by m ; Array to store the last digit of elements in a cycle ; Storing and adding last digit of cycle ; Number of elements present in last cycle ; Sum of k / 10 cycle ; Adding value of digits of last cycle to the answer ; Driver Code ; input n and m
import java . io . * ; class GFG { static long sumOfLastDig ( long n , long m ) { long sum = 0 , k ; k = n / m ; long [ ] arr = new long [ 10 ] ; for ( int i = 0 ; i < 10 ; i ++ ) { arr [ i ] = m * ( i + 1 ) % 10 ; sum += arr [ i ] ; } long rem = k % 10 ; long ans = ( k / 10 ) * sum ; for ( int i = 0 ; i < rem ; i ++ ) { ans += arr [ i ] ; } return ans ; } public static void main ( String [ ] args ) { long n = 100 , m = 3 ; System . out . println ( sumOfLastDig ( n , m ) ) ; } }