Okay, but you could also say<p><pre><code>    19 = 20 - 1
</code></pre>
then multiply by 1.6<p><pre><code>    20 -&#62; 32
    1  -&#62; 1.6
</code></pre>
and get the estimate 19mi = 30.4km, which is even closer and seems rather easier to me than figuring out a set of Fibonacci numbers which sum to 19.