# double digit sums 1-99 * 1-99

How many unique answers are there to all the natural whole numbers 1 - 99 multiplied by all the natural whole numbers 1-99? For instance all the single digits 1-9 multiplied by all the single digits 1-9 yields 32 unique answers between 1& 81. Do the graphs of these 2 problems show any fractal properties. What about 1-999 multiplied by 1-999

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I calculate that there are, in fact, 36 unique products $ij$, with $1 \le i,j \le 9$.

For $1 \le i,j \le 99$, I find 2869 unique products.

For $1 \le i,j \le 999$, I find 247814 unique products.

I'll need to know more about what you mean by "graphs of these 2 problems" to say anything about fractals here.

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– Robert Israel Nov 21 '12 at 7:33
For a graph of first differences see oeis.org/A062854/graph – Henry Nov 21 '12 at 8:01
Thanks for the help matt, I explained more about the graph, it saved as a query/pending edit – fineshigher Nov 21 '12 at 14:22
@fineshigher Great, but I cannot seem to find it anywhere. Could you put it in a comment? – Matthew Conroy Nov 21 '12 at 17:34