Puzzle

1 What is the next number in this series: 23, 9, 20, 14, 14, 9, 20 ... ?

2 What is the next number in this series: 11, 4, 6, 8, 8, 4 ... ?

3 What is the next letter in this series: N, R, X, T, T ... ? (answers tomorrow).

Yesterday's answer: 2 in 3.

Look at it this way: you have a one in two chance of picking the double- headed coin when you will always see a head; you have a one in two chance of picking the head/tails coin, when you will see a head half the time. So, you will see a head on the double-headed coin on 50 per cent of trials and a head on the head/tails coin on 25 per cent of trials. So if you see a head, it's twice as likely to be on the double-headed coin. And if it's a pounds 1 coin, you might also have "Decus et Tutamen" - "adornment and protection" - around its edge.