It appears to be a simple maths question on first glance, but this brainteaser is the latest to have the internet scratching its head.
A debate has erupted over the correct answer to the problem, which reads: 9 – 3 ÷ 1/3 + 1 = ?
The question originally went viral in Japan, where reportedly only 60 per cent of adults could get the right answer.
While the answers have ranged from three to nine, the correct solution relies on a basic rule that you probably learnt at school – but have most likely never thought about since.
The rule, which is remembered using the acronym BODMAS, tells you the order that you must do mathematical operations in – as explained in a video by a maths expert.
It is as follows: brackets, others, division and multiplication, and addition and subtraction.
Using this rule, you must divide three by a third first before completing the rest of the equation.