There are two ways that the contract might be formed with (contracting between persons who are attended and contracting between absence persons).the need for determining the precise moment of the contract , is so clear because there is a specify period separate between the declaration of acceptance and the knowledge with it .and it is clear from the four theories known for jurisprudence (theory of the declaration of the acceptance, theory of exporting the acceptance , theory of the arrival of the acceptance , theory of the knowledge with the acceptance ) . It is difficult to promote one theory on another one if we look at each one and the justification of its supporters and what the opponents of each theory expose. Legal background and different circumstances for each country might have influence in determining the theory that must be adopted to determine the moment of contracting, while the preponderant opinion which represents a base that the supporter of each theory dashing from is the part that worth the protection, so if we want to considerate interest of the offer we will depend then on the acceptance theory or it leas the reach of the acceptance theory. While if we want to take the interest of the acceptor in consideration then we will follow the theory of the declaration of the acceptance or theory of sending the acceptance. United nation convention on contracts for the international sale of good has adopted theory of the arrival of the acceptance. While English law and Iraqi law have adopted theory of knowledge with the acceptance, while the theory of the declaration of the acceptance has been adopted by the Jordanian law.
In order to serve the field of knowledge in the field of design and analysis of experiments by adopting formulas and methods that are easy and simple in arithmetic work, especially in experiments that require many calculations for squares, including tests of type