7.85 billion chips, not 2.2 billion

"Those numbers come on the back of 2.2 billion ARM-powered chips being sold globally in 2011"

That's the Q4 results, not the full year:

"Q4 revenue came from the sales of about 2.2 billion ARM technology-based chips, the highest-ever number of ARM-processor based shipments."

http://ir.arm.com/phoenix.zhtml?c=197211&p=irol-newsArticle&ID=1654432

ARM shipped 1.85 billion in Q1, 1.9 billion in Q2, 1.9 billion in Q3, and now 2.2 billion in Q4. That's 7.85 billion for 2011 in total.