On a chess board, in how many different ways can 6 consecutive squares be chosen on the diagonals along a straight path?
Answer & explanation
Answer: (b) 6
The diagonals of a chess board are its two main diagonals of 8 squares each. A run of 6 consecutive squares fits in 8 − 6 + 1 = 3 positions on each, giving 6 ways.
- 'The diagonals' of a chess board are the two main diagonals, each 8 squares long.
- On a line of 8 squares, 6 consecutive squares can start at square 1, 2 or 3 — 8 − 6 + 1 = 3 ways.
- Two diagonals: 3 × 2 = 6 ways.
- Note: counting every diagonal line of 6 or more squares would give 18, which is not an option — confirming the main-diagonal reading.
Remember · Runs of k consecutive cells in a line of n cells = n − k + 1.
Question and answer: UPSC's official GS Paper II (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·