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?
Answer & explanation
Answer: (d) 0
Zero itself can be reached: 5 − 4 − 3 + 2 × 1 = 0, using minus twice and plus and times once each. No non-negative value can be smaller than 0.
- The smallest possible non-negative value is 0, so first try to make 0.
- 5 − 4 − 3 = −2, so the last part must give +2; and 2 × 1 = 2.
- 5 − 4 − 3 + 2 × 1 = 5 − 4 − 3 + 2 = 0 (multiplication is done first).
- Check the rule: − is used twice, + once and × once, so no symbol is used more than two times.
Remember · For a ‘smallest value’ question, test the smallest option first; one valid construction settles it.
Question and answer: UPSC's official GS Paper II (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·