<PRE><B>Question 865065</B>
&quot;the first two digits cannot be 0&quot;, but they can be any number in the set {1,2,3,4,5,6,7,8,9}


So you have 9 choices for the first two slots. The remaining 7 slots have 10 choices (0 through 9) since 0 is allowed


So you just multiply all the choices for each slot (this is the &lt;a href=&quot;http://www.mathsisfun.com/data/basic-counting-principle.html&quot;&gt;counting principle&lt;/a&gt; in action)



9*9*10*10*10*10*10*10*10 = 810,000,000



as a shortcut you can compute {{{9^2*10^7}}} to get the same answer. 


-------------------------------------------------------



Final Answer: &lt;font color=&quot;red&quot;&gt;810,000,000&lt;/font&gt;



Note: this is the number &lt;font color=&quot;red&quot;&gt;810 million&lt;/font&gt;



Another Note: In scientific notation, the answer is &lt;img src=&quot;http://www.sciweavers.org/tex2img.php?eq=8.1%20%5Ctimes%2010%5E%7B8%7D&amp;bc=White&amp;fc=Black&amp;im=jpg&amp;fs=12&amp;ff=arev&amp;edit=0&quot; align=&quot;center&quot; border=&quot;0&quot; alt=&quot;8.1 \times 10^{8}&quot; width=&quot;81&quot; height=&quot;19&quot; /&gt; Scientific notation is often used for really really large numbers.
</PRE>