<p>@AnAlien. My estimate is that about 1 out of every 5 SATs have a level 5 problem where a quick application of Xiggi’s formula will get you the answer in under 10 seconds. </p>
<p>Other problems will appear where Xiggi’s formula CAN be used, but it may not be the quickest way. I had a nice thread going with an example of this, and a really nice discussion, but unfortunately the moderators deleted it.</p>