In mathematics **Sieve of Eratosthenes** method is one of the best methods for finding prime numbers from 1to 100. This method is very simple and everyone can understand easily this method for finding prime numbers.

Actually, the **sieve of Eratosthenes** method will be learning in lower class that is in class 6 we learn this method. Now let’s see how we can find prime numbers by the sieve of **Eratosthenes** method.

**Follow the below given Steps and find the prime numbers from 1 to 100 by using the sieve of Eratosthenes method:**

First, write all the numbers from 1 to 100 as shown in the table.

Cross “1” as it is not a prime number.

Now leave number “2 “as it is a prime number. Because it contains only two factors i.e. 1 and 2.

Then cross all other multiples of 2 starting with 4.

Next number after 2 will be 3.

It is a prime number as it has only 2 factors like 2.

Now cross all other multiples of 3 starting with 6.

Next number is 4 as it’s already crossed so no problem.

After 4 we have 5. 5 is a prime number, so no need to cross it.

All other multiples of 5 should be crossed know.

Next number is 6, it is already crossed.

After 6 we have 7. It is a prime number, so don’t cross it.

Multiples of 7 cross now.

After 7 we have 8 which is crossed already.

That’s it, now the remaining numbers are called prime numbers. Thanks to **Eratosthenes** for introducing this method for knowing **prime numbers from 1 to 100**. Not only up to 100 Eratosthenes method can be applied to any extent. Just try to find out prime numbers from 1 to 200 by this **Eratosthenes** method.

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