Problem:
How many -digit positive integers have digits whose product equals
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The possible ways of expressing as a product of digits are and . From the first product, the six integers and can be formed. Similarly, six integers can be formed from each of the products and . From the product , the three integers and can be formed. The total number of integers whose digits have a product of is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions