President Jiang Zemin displayed his powers of logic and analytical problem-solving by setting a geometry puzzle during his visit to Macau last week that few Hong Kong students would be able to solve, a maths expert said.
Mr Jiang wrote out the puzzle with an accompanying diagram for the teachers of Hou Kong Middle School, which he visited on Wednesday during his visit to mark the first anniversary of the enclave's return to Chinese rule.
The 74-year-old leader - a secondary school teacher before joining the Government - told the teachers that the problem had been set by his maths teacher when he was in high school. He said the secondary school years were the most important phase of personal development.
'Chinese, English, mathematics and science are all important subjects, particularly mathematics. My favourite subject is mathematics because it is thought-inspiring,' Mr Jiang said.
The geometry problem is composed of a star formed by five irregular triangles surrounded by five circles. The question requires one to prove that points K, L, M, N, O - the intersecting points of the five circles - are on the same circle.
Dr Li Kin-yin, associate professor in the mathematics department at the University of Science and Technology, said reaching a solution to the problem required eight steps.
'To solve this complicated problem, one has to use the known facts and prove the proposition step by step,' he said. 'It is demanding for one's logical inference and observation.'