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The two-digit primes less than 50 are 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, and 47. For each prime on this list whose tens digit is odd, check whether or not the number formed when the digits are reversed is also prime. (Note that if the tens digit is even, then the ``reversed'' number is even and hence not prime.) The palindromic primes less than 50 are 11, 13, 17, 31, and 37, whose sum is 109.
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How many positive integers less than 2101 are divisible by atleast one of the primes?
Except for 1, all of them.
What would be the last prime you would have to sift to find all primes less than 1000?
999 is 111*9 997 is prime, so that is your answer. ■
All odd numbers less than 30 that are prime?
Prime number are number which have exactly two distinct factors, 1 and itself. Odd primes less than 30 are: 3, 5, 7, 11, 13, 17, 19, 23 and 29.
All co primes twin primes. True or false?
False. Co-primes are not the same as twin primes.Co-primes are any numbers having no common factorsother than 1. Examples of co-primes are 8 and 9 or 15 and 32.Twin primes are pairs of prime numbers exactly 2 apart such as 11 and 13 or 659 and 661.
What are all the palindromic numbers?
That's an infinite list.
Sum of all primes less than 100?
The sum of all prime numbers less than one hundred is 1104.
What is the product of all the prime numbers less than 10?
The primes less than 10 are 2,3,5 and 7 with a product of 210.
What is an iterative procedure which determines all the primes less than a given number?
the Sieve of Eratosthenes
How many positive integers less than 2101 are divisible by atleast one of the primes?
Except for 1, all of them.
What is the sum of all of the two-digit primes that are greater than 12 but less than 99 and are still prime when their two digits are interchanged?
472.
What is the sieve of eratosthenes to find prime numbers less than 100?
To find prime numbers less than 100, the sieve of eratosthenes filters out 1 and all multiples of 2, 3, 5, and 7. All remaining numbers less than 100 are primes.
List all the twin primes that are less than 100?
here are all 8, 3,5 11,13 17,19 59,61 29,31 41,43 5,7 71,73
List all the mirror primes less than 100?
11, 13, 17, 31, 37, 71, 73, 79, 97
What would be the last prime you would have to sift to find all primes less than 1000?
999 is 111*9 997 is prime, so that is your answer. ■
What are all the twin primes less than 50?
* 3, 5 * 5, 7 * 11, 13 * 17, 19 * 29, 31 * 41, 43
Why must mersenne numbers be odd?
All Mersenne primes are one less than some multiple of two. Any multiple of two is even, so any multiple one less than a multiple of two must be odd.
Why 113 and 127 are not twin primes?
Twin primes are pairs of prime numbers that differ from each other by two. Examples of all twin primes less than 100 are (3, 5), (5, 7), (11, 13), (17, 19), (29, 31), (41, 43), (59, 61), and (71, 73).
