In three days' time, round £1 coins will stop being legal tender, and you won't be able to spend them in most shops, restaurants and other retail outlets.
But there are still millions of them out there - as much as £420 million worth, according to GoCompare. And across the country, people are checking down the back of the sofa and in children's piggy banks to make sure they find them in time.
"Already over a billion of the 1.7 billion have been returned since the new 12-sided bimetallic £1 coin was introduced back in March over forgery concerns, with the Royal Mint estimating one in 30 round pounds was a fake," explains Georgie Frost, head of consumer affairs at GoCompare.
The deadline for spending the round £1 coins is midnight on Sunday. But if you do find some lying around after that, you will be able to take them to a bank.
We look at the different policies of banks and other organisations on exchanging the round pound.
NatWest and The Royal Bank of Scotland
Customers will be able to pay round pounds into their accounts indefinitely, and will also be able to exchange them for the new 12-sided £1. There's no minimum amount.
Lloyds Banking Group (Lloyds, Halifax and Bank of Scotland)
Lloyds Banking Group says it has no plans to stop accepting old £1 coins from customers: they can be paid into accounts or exchanged, with no minimum amount.
Account holders will be able to pay the old coins in indefinitely, says Barclays.
Santander, too, will accept round pound coins indefinitely, as long as they're being paid into a customer's account. It won't, though, exchange them for the new coins, citing money laundering regulations.
Some stores - such as Tesco, Poundland and Greggs, say they will continue accepting round pounds for a few days after the deadline. Many small independent retailers have said they will do the same.
The Post Office
The Post Office will allow people to deposit their old coins into their accounts with any of the main high street banks.
Incredibly valuable coins
Incredibly valuable coins
This Australian coin was the first half crown minted under Edward VII. The price for a Melbourne coin in good condition is particularly high because around half of them were produced with faults. It’s now worth £7,500 and has risen in value some 13,789% since it was first in production
The only half crown on the list gets its position from its rarity value. However, the fact this is a silver coin rather than a gold one does affect its value - so it’s worth £10,500. It’s significantly less than others on the list - but it has still appreciated 79,445%.
This is the newest coin in the top ten, and the first year that sovereigns were produced featuring the Queen. The coin was produced in small numbers for investors - rather than for circulation - so is thought to be worth £12,500, due to its rarity.
This is another collectable gold coin prized for its rarity value. It’s worth £15,000 today and has appreciated 191,716%
This was issued in very small numbers, as it was produced during WWI. As a result, few are available - especially as uncirculated coins - so one in good condition will fetch £16,000.
This is another coin prized for its rarity, thanks to a relatively low number being minted, and more being taken out of circulation during WWI. It’s now thought to be worth £17,000 after appreciation of 42,084%.
This 1926 coin has shot up in value and is now worth £31,500. The rise in value is partly to do with a very low mintage, and partly to do with the fact that people were asked to hand their sovereigns over to be melted down during WWI, which took many of them out of circulation.
This brass threepence from 1937 has benefited enormously from the fact that Edward didn’t stick around for long to get too many coins struck in his image before he abdicated. It is now worth £45,000.
This 1933 penny has seen a stunning appreciation in value and is valued at a whopping £72,000 today. The value is due entirely to rarity. Only around seven British versions of this coin were minted, and were intended for the King to bury under the foundation stones of new buildings. They have been subject to theft, and a few are said to be in private hands now.
This isn’t the oldest coin in the list, but it was produced in a year when all gold coins were recalled and exchanged for paper money - so the vast majority were melted down. Its rarity and popularity puts it head and shoulders above the rest. It is worth an eye-watering £6,500,000, and has increased in value 2,178,885% since it was produced.