Re: The Number 9 !!!
Another interesting bit of 9 related maths is the number 12345679 (note no 8).
If you multiply this by any single digit multiple of 9, the result is a recurring number of the multiple.
Example: 9X3=27.
12345679X27= 333333333. Note that there are nine digits in the result.
If the multiple of 9 is two digits, similar results occur, try 90, 99 and 108.
There is some science behind these results, based on the concept of place value and the number zero.
Because 9 is the highest single digit number in the decimal system, the next number adds 1 to the value of the place to the left, and resets the first place to zero.
This is an extremely important concept in mathematics. The Romans did not have a symbol for Zero, hence their very cumbersome construction of large values.
It is not certain when the concept of zero and place value were first understood, but it is claimed for both Greek and Muslim scholars.