No current circulating British coin has a diameter of exactly 3 cm. The closest is the £2 coin with a diameter of 2.84 cm.
In the UK, the highest value coin in current wide circulation is the £2 coin.
A UK one pence coin has a diameter of 20.32 millimetres. A two pence coin has a diameter of 25.9mm. A five pence has a diameter of 18mm. A ten pence has a diameter of 24.5mm. A twenty pence is heptagonal and has a diameter of 21.4mm. A fifty pence is heptagonal and has a diameter of 27.3mm. A one pound coin has a diameter of 22.5mm. A two pound coin has a diameter of 28.4mm.
The British two pence coins issued from 1971 through 1992 are bronze, 25.91mm in diameter, and weigh 7.12 grams. Composition was changed in mid 1992 to copper-plated steel (although there do still seem to have been some bronze coins issued through 2000), which are 25.86mm in diameter and weigh 7.14 grams.
Sounds like an Indian coin - not UK?
The Royal Mint did not produce any gold coins in 1971. The closest in appearance to a gold coin would be the 2 New Pence, 1 New Penny and Half New Penny coins which are all made from bronze and have the denomination of the coins inscribed on the reverse. The 2 New Penny coin is 25.91 mm in diameter and has the Welsh plumes on the reverse. The 1 New Penny coin is 20.32 mm in diameter and has a crowned portcullis on the reverse. The Half New Penny coin is 17.14 mm in diameter and has a crown on the reverse.
A decimal penny used in the UK, has a diameter of exactly 2 centimetres (20 millimetres). Therefore, use either cm or mm.
A 5p coin, used in the UK, is made from a metal alloy called nickel-brass, which consists of 75% copper and 25% nickel. This composition gives the coin its distinctive golden color and durability. The coin features a diameter of 24.5 mm and a weight of 3.25 grams.
It depends on the nation. The smallest circulating US coin is a dime, but for other countries it really depends. But the smallest historic coin that the US has minted for circulation is the silver three cent piece.
The circulating British one pound (£1) coin is minted from a nickel-brass alloy of approximately 70% copper, 24.5% zinc, and 5.5% nickel. The coin weighs 9.50 grams (0.34 oz) and has a diameter of 22.50 millimetres (0.89 in.).
Such a coin does not exist. The Royal Mint produced no copper (or bronze) Twopence coins from 1798 until decimalisation in 1971. If such a coin did exist, it would be something in the order of 36 to 41 mm in diameter and very heavy (significantly larger and heavier than a Penny coin from the same period). If the coin is very badly tarnished, you may have a sterling silver Maundy Twopence which would be 13 mm in diameter. George V on the obverse and a crowned 2 on the reverse.
It was the 20pence coin
The UK does not have a president, current Prime Minister is David Cameron