Open Middle®
Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to make the smallest (or largest) product.
Hint
What does the number on the left represent? What does the number on the right represent?
Answer
96 · 87 is one answer for the largest product. 13 · 24 is the smallest positive product and -96 + 87 is one answer for the smallest negative product.
Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both.
Source: Robert Kaplinsky