Hmm that&#x27;s interesting - I&#x27;d tend to round one of the numbers, whichever is closest to a &#x27;5&#x27; or &#x27;10&#x27;, to make an &#x27;easier&#x27; multiplication, then add &#x2F; subtract the extra value lost &#x2F; gained by rounding.<p>Example 9 x 14 = (&lt;10&gt; * 14) - ([1] * 14) = 140 - 14 = 126<p>key: &lt;&gt; easier rounded number [] deal with rounding &#x27;error&#x27;