Problem:
A list of numbers is formed by beginning with two given numbers. Each new number in the list is the product of the two previous numbers. Find the first number if the last three are shown:
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Working backward from , divide each number [e.g. ] by the preceding number [e.g. ] to get the previous number [e.g. ] in the list. Thus , and so on:
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions