Prime Number Tutorial

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Determine if a number is Prime:

This Page presents the user with the chance to determine if a certain number is prime. The calculation is accurate up through a number 16 digits long.

This page can help with determining the Least Common Denominator of Numbers. It is also a good idea to review the divisibility test criteria listed at the bottom of the page.

Please enter a number and then press the Determine button:

Divisibility Tests:

A Natural Number is Divisible by


If the Number is Even


If the Sum of the Digits is divisible by 3


If the last 2 digits is a number divisible by 4


If the last digit is 5 or 0


If the Number is even and divisible by 3


If the number is divisible by 4 and the result is even


If the sum of its digits is divisible by 9


If the last digit is 0

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Email Jim Dildine
Date Last Modified: 8/31/99
James P. Dildine