Soru

Zorluk: KolayModular Arithmetic

What is the value of (−17×5)(mod6)(-17 \times 5) \pmod{6} expressed in standard non-negative remainder form?

  1. A
    −1-1
  2. B
    11
  3. C
    33
  4. 55Cevap

Cevap

55
Multiplying −17-17 by 55 yields −85-85. When −85-85 is divided by 66, the closest multiple of 66 below −85-85 is −90-90. The non-negative remainder is −85−(−90)=5-85 - (-90) = 5, which belongs to the canonical set {0,1,2,3,4,5}\{0, 1, 2, 3, 4, 5\}.

Adım Adım Çözüm

1
Multiply the numbers inside the parentheses
−17×5=−85-17 \times 5 = -85
Perform standard multiplication before applying the modulo operation.
2
Express the negative number in terms of the modulus 6
−85=6×(−15)+5-85 = 6 \times (-15) + 5
Find the largest multiple of 6 less than or equal to -85, which is -90.
3
Extract the canonical non-negative remainder
55
In standard modular arithmetic, remainders must lie in the range [0,n−1][0, n-1], where nn is the modulus.

Anahtar Kavram

Modular Arithmetic and Non-Negative Remainders
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