int m = 9;
    int n = 4;
    m += n;
    n = m - n;
    m = m - n:
    System.out.print (m + "      " + n);

      for (int i = 1; i <= 6; i++)
        if ((i <= 4) && (i > 2))
            System.out.print("      " + i);  

     class Prob4
     {
         static void silly ()
         {
               int temp = x;   x *= y;   y = temp;
         }
         
         public static void main( String [] args )
         {
               int x = 3;     int y = 4;
               silly();
         }
     }

     .  .  *  .  .
     .  *  *  *  .
     *  *  *  *  *
     .  *  *  *  .
     .  .  *  .  .

    class Prob6
    {
        public static void main
        {
            final char STAR = '*';
            final char  DOT = ".";
        
            for (i = 1; i < 5; i++)
            {
                for (int j = 1; j <= 5; j++)
                    if ( (i-3) * (i-3) + (j-3) * (j-3)) < 5
                        System.out.print(  STAR  );
                    else System.out.print( "  " + DOT );
            }
        }
    }

OK, let's see if we can list the errors... You may want to count braces and parens, but unless you're told to do so you should only consider them errors when the compiler would complain about them.
   


1.	( String [ ] args ) is missing next to main
2.	DOT has its type declared as a char, but is assigned to a String - it should be set equal to '.'
3.	The type for the counter i is not declared; it should be written as int i.
4.	There are 5 rows in the picture, so the loop with i needs to run 5 times; therefore it should test i <= 5.
5.	In the if statement, the closing paren is before the conclusion of the statement - move it outside the 5 so that it reads if ( (i-3) * (i-3) + (j-3) * (j-3) < 5 ) ...
6.	In the if/else, the STAR is printed without accompanying space, although space shows in the picture above - add the space shown with printing DOT also to the printing for STAR.
7.	As written, everything will be printed on one line - at no point is there a newline printed. In the picture, we need a newline each time the row changes, so add a System.out.println() statement after the inner for loop.

      
We realize that you were told to use curly braces, and there are times they are omitted in the code above. However, while we DO want you to use them, they are a style issue rather than an error, so they would not count in the errors above.

class Prime
{
    public static void main( String [] args )
    {
        int count = 0;   //  variable to count the number of divisors
                         //  Note - we could also add up divisors and test the sum = 0
    
        //  the first loop will go through the numbers we've been asked to test...
        for( int number = 101; number <= 201; number++ ) {
   
            //  the second loop will look for divisors, going from 2 to the number being checked
            //  We really only need to test divisors up through the number/2, but going through them
            //  all is fine on the test...
            for( int divisor = 2; divisor < number; divisor++ ) {
 
                //  Look for a quotient of 0 - if so, we have a divisor and we count it
                if( number % divisor == 0 ) {
                   count++;
                }
            }  //  ends inner loop doing divisors
   
            //  Now we need to see if we counted any divisors; if not, we have a prime!
            if ( count == 0 ) {
		        System.out.println( number + " is a prime number." );
            }
            
            //  Finally, we reset the counter to 0 before we go on the the next number
            count = 0;
        }  //  closes outer for loop going through the numbers from 101 - 201
    }      
}