LONDON (AFP) � A British mathematician has devised a formula to predict whether loved-up couples are bound to spend their lives together or end their marriages in divorce.

Oxford University professor James Murray said his formula successfully predicted whether a couple would divorce 94 percent of the time, in a study of 700 newly-married couples.

"Some couples might as well get divorced right away," said Murray, who was to present his findings to the Royal Society in London on Thursday, after receiving one of its oldest awards.

As part of the research Murray and his team filmed the newlyweds discussing contentious issues such as money or sex for 15 minutes, and graded each statement made during their respective turns of speech.

Statements with humour or affection were given positive scores, while those with defensiveness or anger were given negative ones. The resulting scores were used to identify whether the relationship was likely to stand the test of time.

The couples were then contacted over one to two year intervals over a period of 12 years, with Murray's formula correctly predicting the divorce rate with an accuracy of 94 percent.

"What astonished me was that a discussion, sometimes highly charged and emotional, could so easily and usefully be encapsulated in what is actually a simple mathematical model of a couple's interaction," Murray said.

In separate research presented at the Royal Society's Bakerian lecture, given by the winner of the annual Physical Sciences prize, Murray found that high-grade brain tumours are much more predictable than is generally thought.

Using two MRI scans taken before a patient undergoes treatment, Murray found that patients would often be better off avoiding surgical removal of the tumour, and could predict the patient's approximate survival time.