A Taranaki woman who can't read numbers is helping to open doors to thousands of other people who struggle with maths.
Hannah Hughson, 28, can't read speed limits, shop prices or recipes.
"Those [road] signs don't mean anything to me. At 50, I'd be going 5k," she said.
She avoids shopping and cooking.
But in a two-year collaboration with Gary Sharpe, her maths support tutor at the Western Institute of Technology at Taranaki (WITT), she has analysed the numeracy tests of 177,000 New Zealanders to find our most common mistakes and suggest ways to fix them.
Sharpe, who has been "in tears at times working with Hannah", believed she had opened the door for others suffering from "dyscalculia" - a kind of wiring in the brain that lacks the connections most of us use to understand numbers.
"Hannah is the most profoundly dyscalculic person we have tested," he said.
She was good at all her other subjects at school and, as the daughter of an accountant, she was expected to be good at maths.
But she wasn't. Her Her parents tried everything; including getting her specialist tuition.
There, she finally found someone who refused to give up on her; 66-year-old Sharpe; a former mechanic.
Sharpe's first thought was to dodge the maths with a calculator. But Hughson couldn't read symbols such as "+, -, x" and developed her own system of always pressing one key for "add", another for "subtract", and so on.
"So I took all the keys off and swapped them over to what she was using," he said.
Eventually he replaced the symbols with words.
"'Add' I can read," Hughson explained. "'One' I can read, 'two' I can read."
But Sharpe was still puzzled because Hughson had no idea whether the calculator gave her correct answers.
"Say I wrote the number 3, but the number 2 was bigger in size. If I said which is the bigger number, she'd say number 2 every time, she's ordering them by size rather than value," he said.
Sharpe started researching, and discovered dyscalculia. He used a WITT scholarship to contact experts in Britain, and developed resources using charts and colour-coding, which Hughson could understand, instead of symbols.
Between them, Sharpe and Hughson have analysed all the maths answers submitted on the Tertiary Education Commission's online Literacy and Numeracy for Adults Assessment Tool in 2016 and 2017 - 3.6 million answers submitted by 177,000 people.
They found that the biggest error rate, 54 per cent, was on "proportional reasoning" questions such as, "If three lollies cost 10 cents, how much will 12 cost?"
Amazingly, Hughson coped with enormous spreadsheets of data.
"It's not working with numbers, it's the formula behind the numbers," she explained. "That was okay because the formula is writing."
Canterbury University psychologist Dr Anna Wilson, who runs the website AboutDyscalculia.org, said Hughson was on the "severe" end of a spectrum which affects about 6 per cent of people.
She said scientists had found an area in the brain that allowed even animals and human infants to judge quantities.
"So the working hypothesis is that for people with dyscalculia, that area of the brain isn't working well, it's not connected to other areas as it could be," she said.
The good news is that the brain is "plastic" and can build connections with practice.
"None of the interventions are quick or easy, they are all like a lot of work over a long time," she said.
What is dyscalculia?
• Dyscalculia is severe difficulty in maths which is not explained by general low intelligence or social issues.
• Caused by a core lack in the ability to judge the number of objects in a set, an ability that underpins all maths.
• Linked to different brain wiring with weak connections that most of us use to process numbers.
• Affects about 6 per cent of people to varying degrees.
Source: Dr Anna Wilson, aboutdyscalculia.org