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Prime Numbers!

  • Project
  • 1 hint
  • 5 of 7 in this chapter

Prime numbers?

In this project, we will write a program that lists all the prime numbers within a certain range of numbers.

A prime number is a number that cannot be divided by any number besides 1 or itself, for the answer to be a whole number.

For example, 2,3, and 5 are prime numbers. But 6, 8, or even 9 aren't.

Challenge

  • Create a list of numbers from 1 to 100 (or any range you’d like)
  • Use a for loop to loop over each individual value in that list
  • Use a while loop on each individual number x, looping over all numbers smaller than x to see if x/one of the numbers is a whole number.
    • If it is, then the number is not prime and should be tossed, then move on to the next number and check.

Hints

Hint 1What is a prime number?

A prime number is a number that cannot be divided by anything besides 1 and itself.

Solution

Swift
let numbers = 1...100
for number in numbers {
 var prime = true
 var i = 2
 while i < number {
 if number % i == 0 {
 prime = false
 break
 }
 i+=1
 }
 if prime {
 print(number)
 }
}

Give the project a try first.