David Todd, 37, of Cromwell Street, Millfield, Sunderland, entered retail premises such as shops, petrol stations and transport hubs and asked for change.
But he would claim he had been given lesser value notes back – or none at all - after craftily hiding those returned up a sleeve, a court heard.
His ruse led to him defrauding 16 businesses of around £600 in total between November 4, 2020, and October 26 last year.
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Premises targeted included Southside Service Station at Peterlee, Newcastle Road Post Office, Sunderland, and Harton Convenience Store, in South Shields.
Todd also struck at a service station at Bedlington, Northumberland, a jewellers in Darlington, and a newsagent in Crook, Co Durham – and 10 other outlets.
At South Tyneside Magistrates’ Court, the dad-of-two pleaded guilty to 16 charges of fraud by false representation, for which he could be jailed.
Prosecutor Paul Anderson said: “Suffice to say the defendant goes into shops or other retail premises and asks for change.
“He asks if they can change a £20 note to two £10 notes, and slides them up his sleeve and says, ‘Where’s my £10 notes?’
“It’s the same modus operandi all the time. The total loss is just over £600 but there’s a large number of offences.”
Mr Anderson said Todd was previously well-known to the courts from past offending but had not been in trouble since 2017.
Alaister Naismith, defending, said: “He’s what you might call an old-fashioned confidence trickster.
“The offences are over a long period of time, about one year, and they are not overly sophisticated.
“They are all £10 and £20, and at a rough calculation it is about £580.
“His record might push him into the custody threshold, but he’s been out of trouble since 2017.
“He has a gambling addiction, he’s resorted to this because of the gambling addiction.”
District Judge Paul Currer adjourned the case for an all-options pre-sentence report.
It means Todd could be jailed when sentenced at the same court on Tuesday, February 8.