A professor of mathematics has worked out an equation to calculate how long into a car journey it takes a child to ask: "Are we nearly there yet?"

The inevitable and often repeated inquiry is set to ring out across the UK as schools break up for the summer holidays today.

Now drivers on long, hot car journeys along Britain's traffic-choked roads will be able to predict exactly when the little backseaters will first ask the question.

Professor Dwight Barkley, of the mathematics department at the University of Warwick, uses a number of factors to work out the equation, by calculating the time you finally get all the kids in the car and eventually leave the house, the number of children in the car and the on board activities to keep the youngsters occupied.

The equation, was commissioned by car firm Skoda, ahead of launching its new family car, the Roomster.

Prof Barkley explained: " Mathematics can help answer many of life's questions and this equation can be a fun way to think about the problem of keeping children entertained on a car journey."

The mathematical explanation of the equation is that the time it takes for a child to ask the question equals: one, plus the number of activities to do, divided by the number of children in the car squared.

To get the final answer, that figure is then added to the time it took the family to get into the car and set off on their journey.

Catherine Bell, from Skoda UK, added: "We assisted the research to better understand factors to consider before a long holiday trip.