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| | Modular Arithmetic, Fermat Theorem, Carmichael Numbers - Numericana |
 | | Note that, when the moduli are not pairwise coprime, some potential sets of "remainders" are ruled out: For example, no integer can leave a remainder of 2 when divided by 6 and a remainder of 3 when divided by 4... |
 | | Modulo 10, for example, the reciprocal of 7 is 3, whereas 1 and 9 are their own reciprocals (the residues 0,2,4,5,6,8 are not coprime to 10 and have therefore no reciprocal modulo 10). |
 | | There are 72 residues coprime to 91 (72 is the Euler totient of 91). |
| home.att.net /~numericana/answer/modular.htm (3088 words) |
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