Zernike的专栏

A positive integer p is called prime if it has just two divisors, namely 1 and p.  By convention 1 is not prime number.The numbers have three or more divisors are called composite. Any positive  int

We define the greatest common divisor of two integers m and n is the largest integer that divides them both. gcd(m,n) = max{k | k/m and k/n}. One of the nicest properties of the gcd is that it is

First, let we see a infinite sum: S = 1+1/2+1/4+1/8+1/16+..... is equal to 2,beacause if we get 2S = 2+1+1/2+1/4+1/8+...=2+S => S= 2. On the other hand,this same reasoning suggests that we ought

Level 1. Given an explicit object x and an explicit property p(x),prove that p(x) is true. Level 2. Given an explicit set X and an explicit property p(x),prove that p(x) is true for all x in X. Le