Activity › Discussion › Math › Find Prime Numbers › Reply To: Find Prime Numbers

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The Sieve of Eratosthenes is a special way to find prime numbers. Prime numbers are special numbers that can only be divided by 1 and themselves. The sieve is named after a clever mathematician from a long time ago called Eratosthenes.
To find prime numbers between 1 and 100 using the Sieve of Eratosthenes, we start by making a list of all the numbers from 2 to 100. We think that all of them are prime at first. Then, we begin with the first prime number, which is 2. We mark all the multiples of 2 as not prime. Next, we move to the next unmarked number, which is 3. We mark all its multiples as not prime too. We keep doing this until we reach 10, which is the square root of the biggest number we have, 100. After that, all the numbers left are prime!
So, after using this special way, we find these prime numbers between 1 and 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97.
These 25 numbers are all prime between 1 and 100. The Sieve of Eratosthenes helps us find them quickly by crossing out the numbers that are not prime.
Using the Sieve of Eratosthenes is a cool way to find prime numbers. It’s used by mathematicians to solve problems and discover new things. It’s simple but really useful!
So, by using the Sieve of Eratosthenes, we can find prime numbers easily and quickly. In this case, we found 25 prime numbers between 1 and 100.