# 19

19 is a prime number.

19th Nervous Breakdown was a hit for the Rolling Stones in 1966. It reached No 2 in both the UK and USA charts.

Paul Hardcastle's 19 was a No1 chart hit in the UK in 1985. Although it was about the American war in Vietnam, the single only reached No 15 in the USA charts.

The Nineteen Propositions were demands put to Charles I by Parliament in 1642 intended to limit the power of the Crown. The king's rejection of them led to the English Civil War and his execution.

To talk 'nineteen to the dozen' is to talk 'the hind legs off a donkey' or to talk 'a blue streak'.

In the game of cribbage 19 is an impossible hand.

19 is a centred hexagonal number. These are numbers which can be arranged into a pattern of concentric hexagons, as in the illustration. There are a series of numbers that can be arranged like this -

7, 19, 37, 61, 91, 127, 169 ...

You will always get a centred hexagonal number if you take a triangular number, multiply it by six and add one.

This pattern of 19 circles is easy to make with coins. It shows that 19 is a 'centred hexagonal number'.