Finding Prime Numbers

In a file called finding_primes.py …

Write a function like so:

def is_prime(n: int) -> bool:
    """Determine whether or not a number is prime.

    Args:
        n: the number to check
    
    Returns:
        True if the number is prime, False otherwise.

    """

Remember that a number is prime if is isn’t evenly divisible by anything except for 1 and itself. You can figure this out by using a for loop inside the is_prime function.

Make the f loop run through all the numbers from 2 up to n. Inside the loop, use an if statement that determines if n is evenly divisible by your loop counter variable.

If you find any number which divides it evenly, you can go ahead and return False from the function without finishing the loop.

If the loop finishes and doesn’t find any numbers which divide it, then return True from the function.

After you finish writing the function write a main() function that contains another for loop. Have it print out all the numbers from 2 to 20, and mark each prime number with a "<".

2 <
3 <
4
5 <
6
7 <
8
9
10
11 <
12
13 <
14
15
16
17 <
18
19 <
20

If you prefer, you may print out only the prime numbers up to 100 or so, like this:

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

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©2021 Daniel Gallo

This assignment is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.

Adapted for Python from Graham Mitchell’s Programming By Doing