A Welsh professor and his son have developed an electronic calculator that allows users to write arithmetic problems on a screen and get the answer.

Harold Thimbleby of the University of Swansea said that his calculator is far more accurate than conventional ones because people can simply proceed as if they were doing a calculation on paper, New Scientist reports.

The calculator could be incorporated into hand-held computers.

Thimbleby and his son, Will, tested a group of people with both conventional calculators and the new one. They found that the subjects got the wrong answer more than half the time with the conventional machines and only 19 percent of the time with their calculator.

Conventional calculators using buttons and require numbers and operation signs to be punched in a certain order, and mistakes are easy to make and hard to spot. On Thimbleby's interface, the inventor said, mistakes are harder to make and easy to catch.

Copyright 2005 by United Press International