3 people know a fact in 1st day. In 2nd day they share it with 3 people each=3×3 Now 3×3 people shares it with 3 people each. and so on... So, 3+3²+3³+3⁴+3^5+3^6+3^7 =3279 no of people altogether , will hear from 1st day to 7th day... On the day 7,no of people who will hear the fact=3^7=2187
