Negative residues make finding modular inverses easier by replacing a large positive representative with a smaller-magnitude equivalent residue modulo m. This often turns the problem into finding the inverse of a simpler number, like -1 or -2, which can be recognized immediately or factored more easily.
Conditions: The replacement must be congruent modulo the same m.; The resulting residue should still be invertible modulo m.
Negative residues make finding modular inverses easier by replacing a large positive representative with a smaller-magnitude equivalent residue modulo m. This often turns the problem into finding the inverse of a simpler number, like -1 or -2, which can be recognized immediately or factored more easily.
Conditions: The replacement must be congruent modulo the same m.; The resulting residue should still be invertible modulo m.