37 asteriscos

import java.util.*;
public class asteriscos{
     
         public static void main(String[] args){
              int num,a,b;
              Scanner cal=new Scanner(System.in);
              System.out.println("Ingrese un numero");
              num=cal.nextInt();
               
               for(a=1;a<=num;a++){
                   for(b=1;b<=a;b++){
                       System.out.print("*");
                   }
                   System.out.println(" ");
                  
                }
         }   
}