MSH! Classes -- Divisibility Tests

 Divisible by 1 -- every number 2 -- last digit is even -- 0, 2, 4, 6, or 8. 3 -- sum of the digits is divisible by 3. Repeat as needed. 4 -- last two digits divisible by 4, or if these are both 0, last 3 digits divisible by 4. 5 -- last digit is a 0 or a 5. 6 -- divisible by both 2 and 3, the prime factors of 6. 7 -- (the number created by all but the ones digit) - 2x(ones digit) is divisible by 7. Repeat as needed. 8 -- last 3 digits divisible by 8. 9 -- sum of the digits is divisible by 9. Repeat as needed. 10 -- last digit is 0. 11, 13 -- See "A divisibility test for 19" by John Greenacre 12 -- divisible by both 3 and 4.

 Other Resourses -- Click Arrow to Open A Window & Make the Jump     "Prime Factorization Puzzle/Practice," a prime recognition and prime factorization board. Come play.     Primes Spreadsheet, with a prime factorization of whole numbers from 1 to 122, whole numbers from from 1 to 500 with primes marked in color, a 50 by 50 times tables     Prime Factorization Text File, prime factorization of whole numbers from 1 to 122     Sample from Tables of Prime Numbers from 2 to 15,000,000,000 by Charles Dean Pruitt, a large list of ordered prime numbers.     The First 1,000 Primes from Prime Curios!, by G. L. Honaker, Jr. and Chris Caldwell     A Primality Test by G. L. Honaker, Jr. and Chris Caldwell, of Prime Curios!    Factorization Using the Elliptic Curve Method by Dario Alpern, states the prime factorization of a number you type on the page.