Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math

Primality Testing

Dr. Math Home || Elementary || Middle School || High School || College || Dr. Math FAQ

Testing for Primality, a selection of answers from the Dr. Math archives.

Prime Numbers - Dr. Math FAQ
What is a prime number? How can you find prime numbers? What's the 'Sieve of Eratosthenes'? What's the largest known prime?

From the archives:

How does the Sieve of Eratosthenes Work?
How does the Sieve of Eratosthenes work for finding prime numbers?

Testing Prime Numbers
Besides the Sieve of Eratosthenes, what other methods can be used to determine all prime numbers within a given range? Is there a more efficient method?

Large Prime Numbers
Is there an algorithm to determine whether a very large number is prime?

Primality Testing
Is there any fomula to find if a number is a prime?

Prime Number Tests
Is the number 55409243 prime? How can you test to see whether a number is prime?

Primality Test
I want to write a program using Pascal that will verify whether a number is prime.

How Many Primes Are Known?
How many prime numbers are currently known?

Largest Prime Number
What is the largest prime number yet found?

No Largest Prime Number
What's the largest prime number? (proof by contradiction).

Testing primality of 32-bit numbers
What is the best (fastest) way to test if an arbitrary 32-bit number is prime?

Integer Root Checking
Is there a quick way to check whether a number has any roots that are whole numbers?

Return to
Middle School Prime Numbers
High School Number Theory
College Number Theory
Index of Selected Answers to Common Questions

[Privacy Policy] [Terms of Use]

Home || The Math Library || Quick Reference || Search || Help 

© 1994-2015 Drexel University. All rights reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.The Math Forum is a research and educational enterprise of the Drexel University School of Education.