Researchers investigating the pressures facing modern youngsters at school discovered the tests leave many parents stumped.
When tasked with answering sample GCSE maths questions, on average 40 per cent of parents answered incorrectly and nine out of ten adults "struggled" when their everyday maths skills were put to the test.
The survey of 2,000 UK adults was commissioned by Your Life, which aims to show how studying maths and physics can improve career opportunities.
GCSE maths questions those surveyed were asked to answer included:
An ordinary, fair dice is rolled 420 times. How many times is the number 3 expected? - 46 per cent of parents couldn't answer this.
50 raffle tickets are sold for 25p each. The winning ticket is picked at random. Linda buys 14 tickets. What is the probability that Linda buys the winning ticket? - 45 per cent of parents couldn't answer this.
There were some people on a train. 19 people get off the train at the first stop. 17 people get on the train. Now there are 63 people on the train. How many people were on the train to begin with? - 25 per cent of parents couldn't answer this.
(Answers at the bottom).
When asked to convert currency, just half of respondents managed to answer correctly - while 49 per cent struggled to calculate how much interest savings would accrue in a year.
Your Life is dubbing the phenomenon “mathsiety”, with a shocking 18 per cent of Brits avoiding maths of any kind due to a lack of self-belief when it comes to arithmetic.
Edwina Dunn, Your Life campaign chair, said: "There is a worrying lack of confidence when it comes to maths skills.
"As a nation, there are huge challenges ahead in order to improve standards - especially as employers are increasingly looking for people with mathematical prowess."
Four in five of those surveyed said they rely on a calculator when doing sums and six in ten regret not making more effort to get better at maths when they were at school.
In fact, around 60 per cent of parents struggle when helping their children with their maths homework.
A quarter of respondents admitted they have trouble counting their change to see if they have received the correct amount.
And seven in ten people have difficulty working out a budget, while three quarters find it hard converting different measurement units.
Around 70 per cent wouldn't know how to figure out if they have been taxed properly on their payslip.
Despite six in ten Brits saying they consider themselves to have a good standard of maths skills only 23 per cent felt they were better at maths than youngsters sitting their GCSEs.
And although nine in ten respondents agreed that having everyday maths skills is important, just 15 per cent described their abilities as very good.
In comparison, two thirds of UK adults said they were good with words.
Edwina Dunn said: "It seems to be hardwired into our culture, we would never admit to being illiterate, so why do seem to be happy to shrug our shoulders when it comes to numbers.
"It is a collective challenge for us as a nation to shake off this attitude and particularly for the next generation whom are sitting exams in the next few weeks."