Date: 05/17/99 at 11:32:38 From: P. Grabowski Subject: Mod Hello! I have been interested in math (something about prime numbers) but can't find anywhere an explanation of what "mod" is. I am prevented from learning more until I know what it means. Can you help to explain it for me please? It comes in the line a^(p-1) = 1 mod p. Is it something like a remainder? Thank you, Grabowski
Date: 05/17/99 at 14:44:52 From: Doctor Rob Subject: Re: Mod Thanks for writing to Ask Dr. Math. The sentence a = b (mod n) means that n is a divisor of a - b. This sentence is read, "a is congruent to b modulo n." It is something like a remainder, because if you subtract a remainder from the dividend, the divisor will go into the result evenly. Examples: 100 = 86 (mod 7), because 100 - 86 = 14 has 7 as a divisor. On the other hand, if you divide 100 by 7, the quotient is 14 and remainder is 2, and 100 = 2 (mod 7), too. If you need more explanation, write again. - Doctor Rob, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.