Monday he sends it to 3 friends. Those three friends send it each three times. Friend 1 =3 F2=3 F3=3. So, on Tuesday a total of 3 people received it. By Wednesday a total of 12 people received it. for the Thursday each of them had sent 3 more which totals out to 39 people that had received the email from him.
The answer should be 39
