Exact code to spot on rare £50 King Charles banknote as it could sell for £1,000s at auction in days

A RARE £50 King Charles banknote could sell for thousands of pounds at auction in days - but it must have a specific code on it.

The new notes, with the face of the monarch, entered circulation last month and will slowly replace those depicting the late Queen Elizabeth II as they become worn or to meet an increase in demand.

But it's worth keeping an eye out for some of the King Charles III notes in particular that could be worth multiple times their face value.

Each new printed banknote features a unique "serial number" used to identify it.

The serial number starts with a four-digit prefix followed by six digits.

There are 999,000 notes printed and put into circulation - with the six digits at the end ranging from 000001 to 999000.

It has become tradition that when a new banknote is issued, a group with low serial numbers is put aside to be sold at auction.

Spink & Son arranges charity auctions in London - and when the new King Charles notes were released, four actions were arranged.

The first, that took place on June 13, consisted exclusively of £5 notes.

Further auctions took place on June 27 and July 11 - and the next one has been arranged for 2pm on Wednesday, July 24.

Among the notes offered at auction are 258 pieces of £50 with a serial number range of AJ01 000003 through AJ01 002024.

Another 72 additional sets with serial numbers from 002025 through 002998 will also be offered.

It is estimated that the notes with the lowest serial number, such as AJ 01 000003, could be worth thousands of pounds.

The highest bid currently available on Spink's website is £7,000 for the note with the serial number AJ01 000003.

It is followed by a bid of £4,000 for the AJ01 000004 note, £3,500 for AJ01 000005, and £1,100 for AJ01 000007.

Higher serial numbers are estimated to fetch a lower amount, but could still be worth a few hundred pounds - much more than the value of £50.

For example, the note with the serial number AJ01 000019 is estimated to fetch between £950 and £1,250, but the current bid is £280.

The banknote with the serial number AJ01 000021 could fetch between £650 and £950, according to Spink, but the current bid is £110.

On June 13, the highest-selling £5 note went for a giant £11,000.

Dozens of low serial number notes were auctioned off on the same day.

After the £11,000 note, the nine next most valuable banknotes sold for up to £7,000.

On July 11, a rare £20 banknote bearing the face of King Charles sold at auction for £7,000.

It's worth noting that the notes sold at the Spink & Son auctions are unlikely to end up in general circulation.

The auctioneer said most people who buy these rare notes are usually veteran collectors who don't intend to resell them.

That doesn't mean they might not crop up on eBay at some point though, so keep an eye out for them in your spare change.

Some of the new King Charles III notes with low serial numbers have already started selling on the website for up to £3,600.

What makes the above notes so valuable is that they have low serial numbers.

But that doesn't mean if you've not got one with a low figure, it won't be worth a lot.

If you stumble on a banknote of any denomination with an eight at the end of the serial number or a block of eights, it could fetch a lot.

Serial numbers with solid blocks are worth a lot to collectors too. So, if you find one with a serial number ending in 111111, for example.

Do you have a money problem that needs sorting? Get in touch by emailing money-sm@news.co.uk.

Plus, you can join our Facebook group to share your tips and stories