What are the first prime numbers?
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If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. Prime numbers are numbers greater than 1. They only have two factors, 1 and the number itself. This means these numbers cannot be divided by any number other than 1 and the number itself without leaving a remainder. Numbers that have more than 2 factors are known as composite numbers. Examples and Non-examples of Prime Numbers Difference Between Prime Number and Composite NumberThe Sieve of Eratosthenes In third century BCE, the Greek mathematician Eratosthenes found a very simple method of finding the prime numbers. Follow the given steps to identify the prime numbers between 1 and 100. Step 1: Make a hundred charts. Step 2: Leave 1 as it is neither a prime number nor a composite number. Step 3: Encircle 2 and cross out all its multiples as they are not prime. Step 4: Encircle the next uncrossed number, which is 3, and cross out all its multiples. Ignore the previously crossed out numbers like 6, 12, 18, and so on. Step 5: Continue the process of encircling the next uncrossed number and crossing out its multiples till all the numbers in the table are either encircled or crossed out, except 1. So, from the table it is clear that 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 are the prime numbers. There are 25 prime numbers between 1 and 100. Terms Related to Prime Numbers Co-Primes: Two numbers are said to be co-prime if they have only one common factor, that is, 1. It is not necessary for these numbers to be prime numbers. For example, 9 and 10 are co-primes. Let’s verify. Note that pairs of any 2 prime numbers are always co-primes. This is because, out of their two factors, the common factor can only be 1. So, (3, 5), (11, 19) are some examples of co-primes. Twin-Primes: A pair of prime numbers are known as twin primes if there is only one composite number between them. For example, (3, 5), (5, 7), (11, 13), (17, 19), etc. List of Prime Numbers between 1 and 1002, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 There are 25 prime numbers between 1 and 100. List of Prime Numbers between 1 and 2002, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 There are 46 prime numbers between 1 and 200. List of Prime Numbers between 1 and 1,0002, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997. Some Facts about Prime Numbers
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