A higher-level HSC maths paper might be one of the most dreaded tasks a year 12 student could do but for Ian Carragher, it's just one way he fills the days.
The 66-year-old also enjoys spending his time playing golf, taking photos and doing high school exams to keep his mind sharp.
He's just one of the many over-65s enjoying retirement in Australia, and the number just like him is about to grow exponentially.
"I have always felt a need to keep my mind occupied," Mr Carragher said.
"I will always have a newspaper with a Sudoku and a cryptic crossword available.
"I sometimes work through some higher-level HSC Maths papers online just to reassure myself that I can still do them, plus, I love a challenge."
It's a way of life more Australians will be getting used to as the number of people aged 65 and over is expected to grow by more than 50 per cent in the next 20 years, according to research from the ARC Centre of Excellence in Population Ageing Research.
Demographers Dr Tom Wilson and Associate Professor Jeromey Temple from the University of Melbourne conducted the study, providing insights into how Australia's population was expected to change over the next 20 years.
"Based on updated population estimates incorporating 2021 census results, Australia's population in all age groups is expected to grow," Dr Wilson said.
"But the largest proportional growth is expected at the oldest ages."
Australia's population aged 65 and over is projected to grow to 6.66 million by 2041, from an estimated 4.31 million in 2021, an increase of 54 per cent.
100+ age group set to triple
Australia's population aged 85 and above is projected to increase in number from 534,000 in 2021 to 1.28 million by 2041 – an increase of 140 per cent.
"The centenarian population, which means those aged 100 and over, will grow at an even faster rate – increasing by 200 per cent from 5,300 in 2021 to 15,900 by 2041," Dr Wilson said.
The total population of Australia is projected to increase from 25.7 million in 2021 to 32.0 million by 2041.
However, according to the study, in the absence of COVID-19 the 2021 population would likely have been about 26.1 million and the 2041 population about 1 million higher.
Why are these age groups growing?
The rapid projected increase in the 85 and over population, according to the study, is due to a projection of people living longer and larger cohorts reaching the age of 85.
In addition, the uptick in growth from around 2031 onwards is the result of the larger baby boom generation — born between 1946 and 1965 — entering the 85 and over age group
COVID-19 also played a role.
With fewer people migrating to Australia from overseas due to border closures between 2020 and 2021 there was lower growth in the young adult population, according to the research.
In the 2018-19 financial year the net overseas migration totalled 241,000. By 2020-21, it had fallen to -88,000.
This meant more people were leaving Australia permanently than arriving — the first negative migration balance recorded since the 1940s.
Has modern medicine played a role?
The director of the Population Interventions Unit within the Centre for Epidemiology and Biostatistics at the Melbourne School of Population and Global Health, Professor Tony Blakely, says two other major factors are helping Australians grow old – less disease and better cures for those diseases.
"Cardiovascular disease is the poster child of how that has improved," he said.
"Half of the decline is fewer people getting heart disease – they're reducing saturated fat consumption, smoking.
"The other half is they're getting better at treating it."
A mix of science and public health messaging can be thanked.
"Lots of small things have been culminating — researching cardiovascular disease, reducing smoking rates, transferring to a Mediterranean diet — that's a function of science discovery.
"And a huge amount of effort from public health authorities — introducing plain cigarette packaging, public education."
He says, however, there is still the age-old question of: if people are living longer, are they living longer with poorer life quality?
"The answer is, it's about the same," he said.
"As we expand life expectancy, you're also extending the number of years in good quality of health."
Rethinking older populations
Professor Blakely says with more years and higher quality of life, it is important to consider where the over-65 population sits in society.
"If you did nothing and you left at 65 and made no changes to social policy, you're going to have a very heavy load of over-65s being carried by society," he said.
"You can make it more sustainable and recognise people who are 65 to 70, have better quality of health, by lifting the retirement age.
"It changes the balance of the working and retirement – it makes the dependency ratio lift.
"That's the reality — if you're going to live longer, you'll probably be working longer."
He says being innovative about social change can also help make the population more sustainable.
"Over-65s and -67s can have a different role in society — providing childcare, through the voluntary sector – roles that elderly people can provide that help society."
Over 65 and wanting to participate
Like Mr Carragher, Carolyn Parfitt, 66, has found plenty of ways to fill up her day.
The former Sydney Morning Herald writer presents two programs a week on local community radio station Port Stephens FM.
"This is a new skill for me and I have done it for the past four years," she said.
"I enjoy it very much and wish I had discovered radio in my earlier career, although I might not have had the confidence to do so back then. "
At 66, Ms Parfitt is still healthy, spending her time doing gravity yoga — an aerial form of yoga — pilates, bushwalking, swimming, playing tennis and eating healthy.
"Of course, one should look after one’s health as one ages," she said.
"But the earlier you start, the better."
She agrees it is a good thing to encourage older people to participate as much as possible.
"Work is good: using the skills we have built over decades is satisfying: contributing in whatever way is good for one's self-esteem and overall health and has to be of benefit.
"A huge amount of voluntary work undertaken by mature people is extremely valuable — Landcare, community radio, school reading programs, koala sanctuary support, marine rescue, the list goes on and on.
"There is plenty of opportunity if one can afford the luxury of voluntary work and is mobile."
