There's not long to go until the old £1 ($1.32) coins are removed from circulation, meaning you will no longer be able to spend them in shops, restaurants or other retailers.
The new 12-sided £1 coins were released at the end of March and after a period of co-circulation, the deadline for the round coins being discontinued as legal tender is midnight on Sunday.
The Exchequer Secretary to the Treasury, Andrew Jones, MP, said that 1.2 billion round £1 coins have been returned so far.
He said: "The hard work of the British public has paid off and I am delighted that more than 1.2 billion round pound coins have been returned.
"Added together, these coins match the weight of around 3,500 elephants or 900 double decker buses. That is a lot of coins.
"There is still time to get involved and with just a week to go, I would encourage anyone who is yet to do so to dig out their remaining coins before Sunday."
CEO and Deputy Master of The Royal Mint, Adam Lawrence, added: "The round pound has been in circulation for over 30 years but, as the deadline approaches, we are keen to encourage everyone to track down their final coins and use them.
"After the October 15, the 12-sided £1 coin will be the only £1 coin being spent in the UK.
"As the deadline is triggered, we are proud that the security features on the 12-sided £1 coin will help to safeguard our currency for years to come."
Although you might be sad to see the older coin go, the newer version - with its distinctive gold-coloured outer ring and a silver-coloured inner ring - has a number of benefits and has been described as 'the most secure in the world' due to its high-tech features, including hologram technology.
First introduced in 1983, the old coin was pulled as it had become vulnerable to sophisticated counterfeiters, with as many as one in 30 thought to be a fake.
If, after 15 October, members of the public and businesses continue to find round pound coins down the back of sofas, then they can still be banked or donated to charity.
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