On a standard die the dots on every pair of opposite faces add up to 7. Which of the dotted nets (a) to (d) folds into a standard die?

Find the opposite pairs in each net. (a) is a cross: the squares above and below the centre (2 and 5) are opposite, and in the row 1 3 6 4 the squares one apart are opposite (1–6, 3–4). All three pairs total 7. In (b) the row 2 3 4 5 puts 2 opposite 4; in (c) the end squares of the top row, 1 and 3, are opposite; in (d) the staircase puts 1 opposite 4.