Question 3
Place the digits 1 to 7 in the grid so that each digit appears once in every row and once in every column. Each circled number is the product of the four digits surrounding that circle.
The source includes a completed 4-by-4 example explaining the rule and the blank 7-by-7 puzzle:
The source includes a completed 4-by-4 example explaining the rule and the blank 7-by-7 puzzle: