How many riffles mix a deck?

Transcript

A fresh deck runs one to fifty-two. A riffle cuts it, then drops both halves together. Each half keeps its order, so at most two threads of the old order survive. Now drag the riffles up to seven. Each riffle at most doubles them. The deck looks mixed long before it is. Over every possible deck, six ideal riffles sit point six one from a perfect mix. Seven reach point three three, under a halfway yardstick. Try it yourself at Explainer Tools dot com.