奇？偶？

dunwan2tellu

你们认为什么是奇数，什么是偶数？是不是能被２整除就被称偶数，不能的就是奇数。那么在负整数（integer negative)及０ 的集合中是否存在着奇偶之分呢？

dunwan2tellu

这是从Mathworld得到的结论 ：

偶数定义：
An even number is an integer of the form 2k, where k is an integer. The even numbers are therefore ..., -4, -2, 0, 2, 4, 6, 8, 10, ... . Since the even numbers are integrally divisible by two, the congruence n=0 (mod 2) holds for even n. An even number n for which n=2(mod 4) also holds is called a singly even number, while an even number n for which n=0(mod 4) is called a doubly even number. An integer which is not even is called an odd number.

dunwan2tellu

奇数定义：

An odd number is an integer of the form 2k+1 , where k is an integer. The odd numbers are therefore ... -3, -1, 1, 3, ５，７.....

灰羊

奇偶數應該包括正負整數和0
其中0為偶數

dunwan2tellu

灰羊，并不是 ＂应该＂ 而是 ＂肯定＂包括负整几０。