To Find the Sum of N Numbers in the system Verilog

class parent;
  
  //Function finds the sum of natural numbers
  function int sum_n_num(int number);
    return number*(number+1)/2;
  endfunction
  

endclass
module top;
  initial begin
    int num=5;
    parent p=new();
    
    //calling the function
    p.sum_n_num(num);
    $display("sum of %d number is %d",num,p.sum_n_num(num));
    
  end
endmodule

class parent;
  
  //Function finds the sum of natural numbers
  function int sum_n_num(int number);  
    int sum;
    
    //Using forloop construst
    for(int i=1; i<=number; i++) begin
      sum=i+sum;
    end
    return sum;
  endfunction
  

endclass
module top;
  initial begin
    int num=5;
    parent p=new();
    
    //calling the function
    p.sum_n_num(num);
    $display("sum of %d number is %d",num,p.sum_n_num(num));
    
  end
endmodule

to Find the Sum of n odd Numbers

class parent;
  
  //to Find the Sum of n odd Numbers
  function int sum_n_num(int number);  
    int sum;
    
    //Using forloop construst
    for(int i=1; i<=number; i++) begin
      if(i%2 != 0)
      	sum=i+sum;   	
    end
    return sum;
  endfunction
  

endclass
module top;
  initial begin
    int num=5;
    parent p=new();
    
    //calling the function
    p.sum_n_num(num);
    $display("sum of %d number is %d",num,p.sum_n_num(num));
    
  end
endmodule

To find the sum of n even Numbers using system verilog function

class parent;
  
  //to Find the Sum of n even Numbers
  function int sum_n_num(int number);  
    int sum;
    
    //Using forloop construst
    for(int i=1; i<=number; i++) begin
      if(i%2 == 0)
      	sum=i+sum;   	
    end
    return sum;
  endfunction
  

endclass
module top;
  initial begin
    int num=5;
    parent p=new();
    
    //calling the function
    p.sum_n_num(num);
    $display("sum of %d number is %d",num,p.sum_n_num(num));
    
  end
endmodule