Parity can be expressed as: odd odd = even; Even number = even number; Even odd = odd.
It can be inferred from the difference of sum and difference that the sum or difference of any two numbers is odd, so the parity of these two numbers is opposite; If the sum or difference is an even number, the parity of the two numbers is the same.
Extended data:
Through examples, we can better understand the meaning of harmony without difference. Here are two examples to explain:
Example 1 There are 50 true and false questions in an exam. 3 points for each correct answer; 1 point for not doing or doing a wrong question; For a student, * * * you get 82 points; The difference between the number of correct questions and the number of wrong questions (including not doing) is ().
A.33 B.39？ C. 17
Analyzing the question type of "knowing the difference", the number of correct answers+the number of wrong answers (including not doing) =50. If the sum is even, the number of correct answers-the number of wrong answers (including not doing) = even, so choose D.
Example 2 There are four classes in one grade, and the total number of the other three classes is131; The total number of the other three categories except category D is134; The total number of students in Class B and Class C is less than that in Class A and Class D 1. Are there () students in these four classes?
177
Through the analysis of the problem of summing up differences, it can be concluded that the total number of students in Class B and Class C is less than that in Class A and Class D 1.
(A+D)-(B+C) = 1, and the difference is odd, then (A+D)+(B+C) = odd, so b and c are excluded.
Since B+C+D = 13 1, A+B+C = 134 and A +2 B +2 C+D =265, (A+B+C+D) must be less than 265.