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Course notes (chap. 1 Number Theory, chap. 2 ... - McGill University

Course notes (chap. 1 Number Theory, chap. 2 ... - McGill University

Course notes (chap. 1 Number Theory, chap. 2 ... - McGill University

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1 Basic <strong>Number</strong> <strong>Theory</strong><br />

1.1 Definitions<br />

Divisibility:<br />

a|b ⇐⇒ ∃k ∈ Z [b = ak]<br />

Congruences:<br />

a ≡ b (mod n) ⇐⇒ n|(a − b)<br />

Modulo operator: (Maple irem, mod)<br />

b mod n =min{a ≥ 0:a ≡ b<br />

(mod n)}<br />

Division operator: (Maple iquo)<br />

b div n = ⌊b/n⌋ =<br />

b − (b mod n)<br />

n<br />

a ≡ b (mod n) <br />

⟺ <br />

a mod n = b mod n

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