Enigma Number 1669

摘要

Coloured bricks IAN KAY My daughter has 10 equal-sized coloured bricks. Each Is cubic, and has opposite faces of the same colour. The three pairs of opposite faces on each are as follows; Brick 1: yellow, green, red Brick 2; blue, green, green Brick 3: yellow, green, white Brick 4: blue, yellow, white Brick 5: green, red, white Brick 6: yellow, yellow, green Brick 7: yellow, red, white Brick 8: blue, green, white Brick 9: blue, yellow, green Brick 10: blue, blue, yellow My daughter arranged nine of the bricks in a tight 3 * 3 square on the carpet and hid the 10th. The visible face of the centre brick was red, no white faces were visible, and the number of visible blue faces, yellow faces and green faces was the same. By studying the visible faces, but without moving the arrangement, I could deduce which was the hidden brick.