You are right that no adult test will give an IQ that high. However the original definition of IQ was in tests for children, and it was measured as mental age

You are right that no adult test will give an IQ that high. However the original definition of IQ was in tests for children, and it was measured as mental age divided by physical age. Those tests are still used for children, and it IS possible for a 6 year old to get an official IQ of 230 on a test like the Stanford-Binet. Which is exactly what Terry Tao did at the age of 6. Comparisons to adult tests may be problematic. But it remains an officially recorded IQ from a standard test.