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.

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© June 29, 2003 www.mathnstuff.com/math/spoken/here/2class/30/divisib.htm