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Sieve of Eratosthenes



Explanation
In Third Century B.C. a Greek Mathmatician " Eratosthenes " developed a table to List all the Prime Numbers and Composite Numbers between 1 to 100. This method is known as " Sieve of Eratosthenes"
The Table developed by him is as:-

12345678910
11121314151617181920
21222324252627282930
31323334353637383940
41424344454647484950
51525354555657585960
61626364656667686970
71727374757677787980
81828384858687888990
919293949596979899100


The Steps to be followed are as:-
Step 1 = Strike Out 1 because 1 is neither a Prime Number nor a Composite Number.
Step 2 = Write 2 in bold.
Step 3 = Strike Out all the Multiple of 2 other than itself. e.g. 2, 4, 6, 8, 10, 12 ........and so on till 100.
Step 4 = After Step 3, the next non-strike number you will find is 3. Write 3 in bold.
Step 5 = Strike Out all the Multiple of 3 other than itself. e.g. 9, 15, 21, 27, ........and so on till 100.
Step 6 = After Step 5, the next non-strike number you will find is 5. Write 5 in bold.
Step 7 = Strike Out all the Multiple of 5 other than itself. e.g. 25, 35, 55, ........and so on till 100.
Step 8 = After Step 7, the next non-strike number you will find is 7. Write 7 in bold.
Step 9 = Strike Out all the Multiple of 7 other than itself.
Step 10 = Continue this process, untill all the numbers in the table are either Strike out or written in Bold.
Step 11 = All the Strike Out Numbers are Composite Numbers (except 1).
Step 12 = All those numbers which are written in Bold are Prime Numbers.

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