Question

Difficulty: MediumClassification of Numbers

A cryptography algorithm generates a numerical verification key, VV, through a specific two-step mathematical process. First, it determines the value of KK, which is strictly defined as the positive remainder when 26-26 is divided by 77. Second, it calculates the final key using the expression V=K×(18÷6×3)V = K \times (18 \div 6 \times 3). Based on the fundamental classification of numbers, which of the following accurately describes the final value of VV?

  1. It is a positive, even, and composite number.Answer
  2. B
    It is a negative, odd integer.
  3. C
    It is a positive, even, and prime number.
  4. D
    It is a positive, odd, and composite number.

Answer

The final value is 18, which is uniquely classified as a positive, even, and composite number.
By applying the formal definition of the modulo operation, the positive remainder of 26-26 divided by 77 is found by the equation 26=7×(4)+2-26 = 7 \times (-4) + 2, giving K=2K = 2. Next, using the correct order of operations (left to right for consecutive division and multiplication), the expression evaluates to (18÷6)×3=3×3=9(18 \div 6) \times 3 = 3 \times 3 = 9. Multiplying these results yields V=2×9=18V = 2 \times 9 = 18. The number 18 is classified as positive (greater than zero), even (divisible by 2), and composite (having factors other than 1 and itself).

Step-by-Step Solution

1
Determine the positive remainder when 26-26 is divided by 77 to find the value of KK.
K=2K = 2
By the formal definition of Euclidean division, the remainder must be non-negative. We must express 26-26 as 7×(4)+27 \times (-4) + 2, which gives a valid positive remainder of 22.
2
Evaluate the mathematical expression 18÷6×318 \div 6 \times 3 following the correct order of operations.
The expression evaluates to 99.
According to the BODMAS rule, division and multiplication share the same level of precedence and must be evaluated strictly from left to right. Therefore, (18÷6)=3(18 \div 6) = 3, and 3×3=93 \times 3 = 9.
3
Calculate the final value of the verification key VV and classify it.
V=2×9=18V = 2 \times 9 = 18. The number 1818 is a positive, even, and composite number.
The number 1818 is greater than zero (positive), perfectly divisible by 22 (even), and possesses divisors other than 11 and itself, such as 2,3,2, 3, and 66 (composite).

Key Concept

Classification of Numbers and Fundamental Arithmetic Operations
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