Python计算器无分数计算

Question

I'm trying to write a script that will return you all the prime numbers till the number that you entered, and the problem is that if you ask python how much it's 17/2 , it will answer 8, also with 27/2 it will answer 13, how do I fix it ?

I tried float() but it doesn't work.

Edit: The script that I wrote, till now:

array=[2,3,5,7]
num=int(raw_input("Please enter a number higher then 8:    ex:12\n")) 
for i in range(8,num): 
    b=float(i)
    if b%2.0 and b%3.0 and b%4.0 and b%5.0 and b%6.0 and b%7.0 and b&8.0 and b%9.0!=0:    
        array.append(b)
        print array

Answer 1

try this

17 / 2.0 or 

17.0 / 2

Answer 2

If you want to use integers you can use:

from __future__ import division
a = 4
b = 6
c = a / b
print c

Outputs:

0.66666666666666663

Answer 3

You want this I guess

num = 25

primeList=[]
for val in range(2,num):
    if not any(val%i==0 for i in primeList):
        primeList.append(val)

print primeList

for num=25 , it outputs:(python 2.7.6)

[2, 3, 5, 7, 11, 13, 17, 19, 23]

for num=100 , it outputs:

[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,  
 67, 71, 73, 79, 83, 89, 97]