Question 706693
<pre>
Here is a much easier way to do it.
They all start with 347, so we need only consider the
4-digit numbers following that.

There are 10<sup>4</sup> or 10000 4 digit numbers.

From that we must subtract those that are "zero-less OR one-less"

N(zero-less OR one-less) = N(zero-less) + N(one-less) - N(zero-less AND one-less)

                       =       9<sup>4</sup>    +     9<sup>4</sup>     -         8<sup>4</sup>

                       =     6561    +   6561     -       4096 

                       =     9026 
Subtract from 10000, 

              10000 - 9026 = 974

Edwin</pre>