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What is sieve for prime numbers?
The Sieve of Eratosthenes is one such. Write out the numbers 1 to 100 in 10 rows. Cross out 1. Start at 2 and cross out multiples of 2. That will eliminate all the rest of the even numbers. Go to the next uncrossed-out number (3) and cross out all of its multiples. Some of them will already be crossed out. Proceed in this fashion. Five will be next. You can stop by the time you get to ten. All of the uncrossed-out numbers are prime.
What is the sieve of Eratosthenes's?
It is a method for finding the prime and composite numbersHere is an example of the sieve. Firstly the definition of a prime is a number divisible only by itself and one. From that we can build this sieve, it can of course go on as far as you wish. Though with very large numbers it becomes impractical.1 2 3 4 5 6 7 89 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27Then starting at 1 we highlight all those numbers which can be divided by numbers lower than themselves. Each number in bold is not a Prime number because a number below it can be divided into it with no remainder. Each number in italics is a prime, because, as we have said it can only be divided by 1 and itself. It should also be noted that 2 is the only even prime number, all other even numbers can be divided by 2. So if you are asked if a number is prime and it is an even number then you do not have to check because it is not.The Sieve of Eratosthenes is a way of determining which numbers are prime.Zero and one are, by definition, not prime.Write a list of numbers from two up to the highest number in which you are interested.The first number, 2, is prime and every multiple of it can not be prime, so cross them out -- that is 4, 6, 8, 10, and so onThe next number not crossed out will be 3. That is prime but its multiples can't be, so cross them out -- 6, 9, 12, 15, and so on.4 is crossed out, so the next number not crossed out is 5. That is prime, so cross out its multiples, 10, 15, 20, and so on.Continue this process until you can not cross out any more numbers (about halfway down the list)When you have finished, all numbers not crossed out are prime.
How will you use the sieve of Eratosthenes to get all the numbers less than 50?
Write out the numbers 1 to 50 in 5 rows. Cross out 1. Start at 2 and cross out multiples of 2. That would eliminate all the rest of the even numbers. Go to the next uncrossed-out number (3) and cross out all of its multiples. Some of them will already be crossed out. You can stop by the time you get to eight. All of the uncrossed-out numbers are prime.
Explain how would you find all the prime numbers between 1 and 100?
I would use the Sieve of Eratosthenes. Write out the numbers 1 to 100 in 10 rows. Cross out 1. Start at 2 and cross out multiples of 2. That will eliminate all the rest of the even numbers. Go to the next uncrossed-out number (3) and cross out all of its multiples. Some of them will already be crossed out. Proceed in this fashion. Five will be next. You can stop by the time you get to ten. All of the uncrossed-out numbers are prime.
What are the prime numbers between five and fifteen?
5,7,11,13 are prime I would suggest looking into the sieve of erasthenes for further reading. For tests, look at odd numbers and see if odd numbers divide them. ie 9 is not in the lsit because it is divisible by 3. Even numbers are always divisible by two.
