Question

USING PYTHON ONLY

Part 3a: Prime Number Finder

Write a program that prompts the user to enter in a postive number. Only accept positive numbers - if the user supplies a negative number or zero you should re-prompt them.

Next, determine if the given number is a prime number. A prime number is a number that has no positive divisors other than 1 and itself. For example, 5 is prime because the only numbers that evenly divide into 5 are 1 and 5. 6, however, is not prime because 1, 2, 3 and 6 are all divisors of 6.

Here's a sample running of the program:

Enter a positive number to test: 5

2 is NOT a divisor of 5  ... continuing
3 is NOT a divisor of 5  ... continuing
4 is NOT a divisor of 5  ... continuing

5 is a prime number!

And here's another running:

Enter a positive number to test: 9

2 is NOT a divisor of 9  ... continuing
3 is a divisor of 9  ... stopping

9 is not a prime number.

Some notes on your program:

• 1 is technically not a prime number.
• Once you find a number that evenly divides into your test number you do not need to continue testing additional numbers - the number cannot be prime.

Answer 1

Code and output

Code for copying

n=int(input("Enter a positive number to test: "))
while n<=0:
n=int(input("Enter a positive number to test: "))
count=2
for i in range(2,n):
if n%i==0:
print("{} is a divsor of {} ....stopping".format(i,n))
print(" ")
print("{} is not a prime number.".format(n))
break
if n%i !=0:
print("{} is a NOT a divsor of {} ....continuing".format(i,n))
count+=1
if count == n:
print(" ")
print("{} is a prime number!".format(n))

Code snippet

n=int(input("Enter a positive number to test: "))
while n<=0:
    n=int(input("Enter a positive number to test: ")) 
count=2
for i in range(2,n):    
    if n%i==0:
        print("{} is a divsor of {} ....stopping".format(i,n))
        print(" ")
        print("{} is not a prime number.".format(n))
        break 
    if n%i !=0:
        print("{} is a NOT a divsor of {} ....continuing".format(i,n))
        count+=1
if count == n:
    print(" ")
    print("{} is a prime number!".format(n))