CSAT 2024 Solutions - In the expression 5 * 4 * 3 * 2 * 1, * is chosen from +, -, × each at most two times. What is the smallest non-negative value of the expression?

Q6. In the expression 5 * 4 * 3 * 2 * 1, * is chosen from +, -, × each at most two times. What is the smallest non-negative value of the expression?

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A. 3
B. 2
C. 1
D. 0

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Answer: D. 0

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Explanation:

The goal is to minimize the value of the expression by strategically using subtraction and addition while ensuring the result is non-negative.

Approach:

• Maximizing Subtraction: Subtraction will reduce the value of the expression. To achieve the smallest result, we want to subtract as much as possible.
• Addition Strategy: Add numbers only when necessary to prevent the value from becoming negative.

Calculation:

• First, subtract strategically to bring the result to zero:
  5 - 4 = 1,
  1 - 3 = -2,
  -2 + 2 = 0,
  0 × 1 = 0.

By using subtraction, addition, and multiplication in the correct order, we achieve a result of 0.

Thus, the smallest non-negative value of the expression is 0.

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