Jan.1 jerome concocts a rumor and tells

jan 1 jerome starts a rumor and tells beth. on jan 2 they tell a new person. jan 2 four people heard the rumor. on each subsequent day, each person who has heard the rumor spreads it to a new person. how many have heard the rumor by the end of jan 8?

Number of people who have heard it
by the end of the day:

January 1 . . . . . 2
January 2 . . . . . 4
January 3 . . . . . 8
January 4 . . . . . 16
January 5 . . . . . 32
January 6 . . . . . 64
January 7 . . . . . 128
January 8 . . . . . 256
.
.
.
February 1 . . . . .  4,294,967,296
February 2 . . . . . 8,589,934,592  <=== more than the Earth's
                                                           human population.

Because of mourning president bush's death