Australian scientists say they have solved the mystery of a 3,700-year-old Babylonian clay tablet, revealing it is the world's oldest and most accurate trigonometric table.

The scientists from the University of New South Wales in Sydney deciphered markings on the tablet which have mystified experts since it was discovered in the early 1900s in southern Iraq.

They conclude that the tablet was used by ancient mathematical scribes to calculate how to construct palaces and temples and build canals, the team said in a statement released by the university Friday.

Known as Plimpton 322, the small tablet was discovered by archaeologist, academic, diplomat and antiquities dealer Edgar Banks, the person on whom the fictional character Indiana Jones was based.

It has four columns and 15 rows of numbers written on it in the cuneiform script of the time using a base 60, or sexagesimal, system.

"Plimpton 322 has puzzled mathematicians for more than 70 years, since it was realized it contains a special pattern of numbers called Pythagorean triples," said Dr Daniel Mansfield of the School of Mathematics and Statistics in the UNSW Faculty of Science.

"The huge mystery, until now, was its purpose - why the ancient scribes carried out the complex task of generating and sorting the numbers on the tablet.

"Our research reveals that Plimpton 322 describes the shapes of right-angle triangles using a novel kind of trigonometry based on ratios, not angles and circles. It is a fascinating mathematical work that demonstrates undoubted genius.

The new study is published in Historia Mathematica, the official journal of the International Commission on the History of Mathematics.