title: counting the number of prime numbers up to some large value
body: <p>i wrote this super simple python code to count the number of prime numbers up to some large value. The problem is for a value like <code>1e+8</code>the program takes so much time, i want to improve this code for faster result and better performance. 
  here's the code:</p>
  
  <pre><code>import math
  
  def is_prime(num):
      if num%2 ==0 and num&gt;2:
          return 0
      for i in range(3, int(math.sqrt(num)) + 1, 2):
          if num % i == 0:
              return 0
      return 1
  
  def count_prime(num):
      ct=0;
      for i in range(2,num+1,1):
          if is_prime(i)==1:
              ct+=1
      return ct
  </code></pre>