Shederivedanotherformularelating the number of folds possible in one direction (n) to theminimum possiblelength of material (l) and the material's thickness (t)
To power this beast, Xiaomi's throwing in a 2, 000mAh cell, but you can also purchase a 3, 000mAh version if you don't mind the extra 2mm thickness on the phone.
And mind you, we're using the word "ultraportables" very deliberately here: in addition to Ultrabooks, HP is selling so-called Sleekbooks -- lightweight machines that, for whatever reason (thickness, AMD processors), don't fit Intel's definition of an Ultrabook.