Sentence:  The IBM 3380 Direct Access Storage is a disk storage device with a storage capacity of 2.5 <WSD>gigabytes</WSD> (billion bytes) per unit, an increase of almost four times the capacity of the IBM 3350 Direct Access Storage.<!-- 2×2×885×712140 = 2.52e9 bytes --> 
Meaning of the word marked with <WSD> tags:  109, one billion (1,000,000,000) bytes. SI symbol: GB