Send a short message to 10, and the recipient will send it to everyone 10. * * * Send it ten times. * * * How many people received the text message?

1 person sends text messages to 2 people, 2 people send text messages to 4 people,

(1) After 20 times, there is a person who receives the text message at the same time with the power of 2 = 1048576.

(2)*** has 2+4+8+ 16+...+2 to the 20th power.

=2*( 1-2 to the 20th power) /( 1-2)

=2 2 1 power -2 people received the text message.