A person has 2 parents, 4 grandparents, 8 great grand parents, and so on. Find the number of his ancestors during the ten generations preceding his own.
To find number of ancestors, we will find the sum of 2,22,23,......
Number of ancestors S10=2(210−1)2−1
Find the number of ancestors i.e. parents, grandparents, great grandparents and so on, that a person has during the ten generations preceding his own.