Can you crack the ‘Harvard’ brainteaser that ‘has a pass rate of just 10 per cent’?

The internet is often our first port of call when we’re stumped by a question – but the worldwide web is fighting back with a seemingly impossible brainteaser of its own.

In a maths problem that has divided readers, they are told: Seven men have seven wives. Each man and each wife have seven children. What is the total number of people?

The question in its original form appears handwritten on a piece of headed notepaper bearing the logo of Harvard University.

But the riddle’s unlikely provenance appears to be a 2021 Instagram post by rapper Ja Rule, who claimed it was sent to him by a friend as part of a university ‘interview’ process.

The doubts over the question’s actual origin may come from the fact that different interpretations of its ambiguous wording can result in various answers – at least four, according to internet users.

The wording of the question means there appears to be no definitive answer – although the viral image of the brainteaser includes the handwritten claim that “90 per cent [of interviewees] were eliminated”.

Even Ja Rule – a Harvard Business School alumnus after completing an online course – claimed to be stumped.

The rapper, who has collaborated with the likes of Jennifer Lopez and Ashanti, posted to his one million Instagram followers: “The answers are all over the place lol... solve this problem... What’s the right answer?”

SOLUTION 1

If brainteaser fans assume the question implies that seven men have a total of seven wives between them, and each of the seven couples have seven children, the total number of children is 49.

Add the number of adults (14) and the answer is 63.

SOLUTION 2

It could be argued that each man has seven wives. That would mean 49 wives for the seven men, and a total of 56 adults.

If each of those 56 had seven children, 56 multiplied by seven would result in 392 children. Add the number of adults, and the answer is 448.

SOLUTION 3

Considering only that each man and each of his wives – as a couple – have seven children, the equation will be 49 (women) times seven (children), which equals 343. Add the 56 adults, and the total is 399.

SOLUTION 4

Some internet users have assumed that each man and each wife – a total of 14 adults – have seven children each.

This makes a total of 98 children, with the 14 adults making a total of 112.

The contrarians among us have come up with a fifth answer.

This assumes each of the seven men has one wife each, but they share the seven children between them – rather than having that number each.

Seven men, seven wives and seven children gives an answer of 21.

But the wording of the question doesn’t really support this.