<pre>
<pre>
 9^11 = 9 (mod 100), so we need to find 8^...^1 (mod 10).
 8^5 = 8 (mod 10), so we need to find 7^...^1 (mod 4).
 7^3 <code> 7 (mod 4), so we need to find 6^...^1 (mod 2), but this is clearly 0, so 7^...^1 </code> 1 (mod 4) <code></code>>
 8^...^1 <code> 8 (mod 10) </code><code>> 9^...^1 </code> 9^8 (mod 100) = 21 (mod 100).
</pre>
</pre>
