A man starts a chain letter by writing to five friends. Each friend in turn writes to five others. If this is continued for six rounds, how many people will have received the chain letter?

Answer 1

1st round 5 received the letter

2nd round 5x5 +5 = 30

3rd round 25x5 +30 = 125+30 = 155

4th round 125x5 +155 = 625 +155 = 780

5th round 625x5 + 780 = 3125 + 780 = 3,905

6th round = 3125x5 + 3905 = 15625 +3905 = 19,530 received the letter