The 500th anniversary of the birth of the mathematician who invented the equals sign is being celebrated in his home town in Pembrokeshire.
Robert Recorde was the first to write books on arithmetic in English, rather than Latin or Greek, so ordinary people could understand them.
The town's museum is holding an art exhibition, and also offering a chance to read Recorde's work.
Copies of his original books have now been republished.
Recorde, who was the son of the mayor of Tenby, was born in the town in 1510 and went to study at Oxford aged 15.
He has been celebrated not just for his learning but for being ahead of his time in the teaching of maths.
In his 1557 work, The Whetstone of Witte, he writes of the new sign "because noe 2 thynges can be moare equalle".
Although best known as the equals sign's inventor, his importance added up to far more.
It includes bringing the use of algebra to English readers and devising the method of extracting the square root as it is used today.
"He was the founder of the English School of Mathematics, and the first person to write a mathematical book in English that was understandable to the ordinary citizen," said Sue Baldwin, honorary librarian at Tenby Museum.
"He was a doctor, astrologer, a controller of the Royal Mint - polymath is absolutely the correct word."
The museum is welcoming Gordon and Liz Roberts, a Derbyshire couple who developed a serious fascination with Recorde after a visit to Tenby several years ago.
All week they will be presenting a guide to Recorde's work, alongside his original books being displayed at the museum.
Mr and Mrs Roberts have painstakingly recreated facsimile copies of Recorde's mathematical works, republishing the original 16th Century text and drawings.
"The originals have been recreated page by page, it's a real labour of love," said Ms Baldwin.
"They'll be helping people to read the English Tudor text - the spelling is completely bizarre, there was no received spelling in 1557."
Recorde's varied career, which included being royal physician to Edward VI and surveyor of mines and monies of Ireland, ended sadly when he died in a debtors' prison in 1558 after being sued for defamation by the earl of Pembroke.
An art exhibition is also running at the museum, to celebrate Recorde's connection to Tenby.