Arrange the digits 1, 2, 3, 4, 5, 6, 7, 8, and 9 into three groups. Make one group of two digits, one group of three digits, and one group of four digits.
When you multiply the first group of two digits by the second group of three
digits you get the four digit number as your answer.
Example: 39x186=7254
There are six other possible combinations.