When Akshay Venkatesh was 13 years old and had completed his high school studies, he told the ABC he was aiming to "maybe become a mathematician".

Key points: The Fields Medal is known as the "Nobel Prize for mathematics" and is awarded once every four years

The Fields Medal is known as the "Nobel Prize for mathematics" and is awarded once every four years Professor Venkatesh was described as a "prodigy" and a "genius" during his teenage years

Professor Venkatesh was described as a "prodigy" and a "genius" during his teenage years He is being honoured for work that combines insights from several different fields of mathematics

Well, that came true — and then some.

Professor Venkatesh, who graduated from the University of Western Australia aged 16 with honours in pure mathematics, has achieved his subject's highest honour.

He has been awarded the Fields Medal, known as the "Nobel Prize for mathematics" — awarded once every four years to between two and four people under the age of 40.

It is an amazing achievement for the 36-year-old, who was described as a "prodigy" and a "genius" during his teenage years in Perth.

Sorry, this video has expired The ABC met Akshay Venkatesh in 1994 when he was the youngest senior graduate from his Perth high school

Nowadays, Professor Venkatesh is a dad who lives a pretty normal live in the US.

"It's really a prize for younger mathematicians, both about their previous work and to kind of encourage them to keep doing that," he told the ABC.

"I have very normal interests. I go running, that's my main exercise hobby. I like to read.

"But the truth is having young children takes up a lot of time … When I get a chance, I read or go for a run, but I'd say most of my spare time, I'm with the kids."

And for his mum, who is immensely proud of him, she just wants him to be happy.

"That is all I hope for him, that he is happy and he loves what he does," said Svetha Venkatesh, who is herself a professor of computer science at Deakin University, and a leader in the field of machine learning.

Akshay Venkatesh is a professor of mathematics at Stanford University in the US. ( YouTube: Infosys Prize )

Professor Venkatesh, who teaches at Stanford University in California, is being honoured for work that combines insights from several different fields of mathematics.

His former classmate, and now professor of mathematics at the University of WA, Michael Giudici said explaining his work to the general public was hard.

"If it was easy for me to explain, then he wouldn't have received the Fields Medal," Professor Giudici said.

One of Professor Venkatesh's most famous pieces of work is solving what's called the "subconvexity problem".

To do that, he developed new techniques and borrowed from other areas of mathematics, Professor Giudici said.

Here's how Professor Venkatesh describes the work he's been engaged with the most.

Sorry, this video has expired Akshay Venkatesh on dynamics and number theory

This year's three other Fields Medal winners were Italian mathematician Alessio Figalli, Iranian Caucher Birkar, and German Peter Scholze.

In a bizarre footnote to the awards ceremony in Rio de Janeiro, Professor Birkar's medal was stolen. Organisers said they were cooperating with authorities to retrieve the prize.

'It was clear that Akshay was amazingly talented'

Professor Giudici recalled his student days with a very young Professor Venkatesh, saying he was incredibly well adjusted to uni life.

"I know in our fourth year, he was probably one of the main characters in the group — always discussing things other than mathematics," he said.

"We spent a lot of time as honours students talking about cricket."

His mum said that was something she was keen to foster.

"He was a normal, happy child growing up in a normal family," she said. "He never did anything particularly special because he was good at maths. It was just one of those things."

When he started university at the age of 13, one of his mentors was Professor Cheryl Praeger, a fellow of the Australian Academy of Science.

"At our first meeting I was speaking with Akshay's mother Svetha while Akshay was sitting at a table in my office reading my blackboard, which contained fragments from a supervision of one of my PhD students, just completed," Professor Praeger recalled.

"At Akshay's request I explained what the problem was. He coped with quite a lot of detail and I found that he could easily grasp the essence of the research.

"It was clear from the start that Akshay was amazingly talented. He was interested and immediately engaged with all kinds of mathematical questions.

"I was sure that he would achieve a great deal mathematically, and I'm thrilled at his stunning success in being awarded a Fields Medal."

'Australian mathematics is on a real roll'

Professor Venkatesh is just the second Australian to receive the Fields Medal. Dr Terence Tao won the award in 2006.

Comedian and mathematics communicator Adam Spencer said Professor Venkatesh's award was a "great day for Australian mathematics" and the crown in a string of recent achievements from Australian mathematicians.

Adam Spencer says Aussie maths is on a roll. ( 702 ABC Sydney: John Donegan )

"Australian mathematics is on a real roll here," Spencer said.

"First mathematician Geordie Williamson from the University of Sydney was admitted to the Royal Society, making him the youngest member.

"Then Nalini Joshi, also from the University of Sydney was named vice-president of the International Mathematical Union.

"And now Akshay joins our own Terence Tao as a winner of the world's elite prize in mathematics. Boo yah!"

In 2016, when Professor Venkatesh was awarded another prestigious prize, he said doing mathematics gave him a feeling of "transcendence".

"You feel like you've been part of something really meaningful," he said at the time.