A maths professor has worked out an equation to calculate how long into a car journey it takes for your little ones to ask: "Are we nearly there yet?"

According to the BBC, Professor Dwight Barkley, of Warwick University, calculates there are three key factors that decide the timing of the wearisome question.

Crucial in putting off the first prompt about the proximity of the destination are on-board activities for children.

So no activities equals a question before leaving the driveway, he said.

The equation for the time it takes for a child to ask the question is:
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.

So before your leave for that trip down to the beach or to drop them off at grandmas, make sure you pack plenty of gadgets such as a PSP and GPS in the car to keep them entertained.