Nine cards of the color same as the box which numbers from 1 to 9 were written are in the each box.
One card is taken out of each box.
How many ways of taking out are there in total that the product of three numbers becomes 24?
21 ways
Solution
The combination of three numbers that the product becomes 24 is four patterns of (1,3,8),(1,4,6),(2,2,6),(2,3,4).
Color combinations of the cards are three ways in the case of (2,2,6).
There are six ways in the case of other three patterns respectively.
Therefore, there are 3 + 6 × 3 = 21 ways altogether.
