Modulo Multiplication is Well-Defined/Examples

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Examples of Use of Modulo Multiplication is Well-Defined

Modulo Multiplication: $19 \times 6 \equiv 11 \times 2 \pmod 4$

\(\ds 19\) \(\equiv\) \(\ds 11\) \(\ds \pmod 4\)
\(\ds 6\) \(\equiv\) \(\ds 2\) \(\ds \pmod 4\)
\(\ds \leadsto \ \ \) \(\ds 19 \times 6 = 114\) \(\equiv\) \(\ds 11 \times 2 = 22\) \(\ds \pmod 4\)


Modulo Multiplication: $2 \times 3 \equiv -6 \times 15 \pmod 4$

\(\ds 2\) \(\equiv\) \(\ds -6\) \(\ds \pmod 4\) Congruence Modulo $4$: $2 \equiv -6 \pmod 4$
\(\ds 3\) \(\equiv\) \(\ds 15\) \(\ds \pmod 4\) Congruence Modulo $4$: $3 \equiv 15 \pmod 4$
\(\ds \leadsto \ \ \) \(\ds 2 \times 3 = 6\) \(\equiv\) \(\ds \paren {-6} \times 15 = -90\) \(\ds \pmod 4\)