Which of the following is not a valid denomination for UK coins?

Okay, let's talk about UK coinage. The British currency system is decimalised, meaning it's based on units of ten, which was introduced in 1971. Before that, the UK had a more complex system with shillings and pounds divided into different amounts. Since decimalisation, the coins in circulation have been carefully chosen to make transactions easy. You'll find 1p, 2p, 5p, 10p, 20p, and 50p coins, as well as £1 and £2 coins. A 25p coin has never been a standard denomination in the UK. While commemorative coins of 25p value have been issued on occasion, they are not for general circulation. So, if you're asked about valid UK coin denominations, remember that while 20p, 5p, and 10p are all part of your everyday change, you won't find a 25p coin in your wallet!