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iOS

Raghavendra Temkar
Raghavendra Temkar
677 Points
Posted by Raghavendra Temkar
Raghavendra Temkar
677 Points

how to find a set of prime numbers in a range

I would like to find out what numbers are prime in a given set ... say numbers between 1 and 20. So prime numbers are not divisible by any other number except the number itself.

so for numbers between 1 and 20, i need to check if the number is divisible by any number in the given range. I use this code but it is not working 

var x = 1
var i = 1
while x <= 20 {

    if ((20 - i) % x  == 0) {

        print("\(x) is not a prime number")
}
    x += 1

}

1 Answer

Jeff McDivitt
Jeff McDivitt
23,970 Points
Jeff McDivitt
Jeff McDivitt
23,970 Points

One way you could do it is by using a for in statement 

for number in 1...20 {

    if number % 2 != 0 {
        print("\(number) I am not a prime number")
    }
}
Raghavendra Temkar
Raghavendra Temkar
677 Points
Raghavendra Temkar
Raghavendra Temkar
677 Points

this will only tell me if. number is even or odd, not whether its a prime number