In 1980, the computer hard disk had a maximum capacity of 10 to the 7th power bytes. In 2000 computer hard disk capacity had increased to 10 to the 11th power bytes. By what factor had hard disk capacity increased between 1980 and 2000?
10^11/10^7 = 10^4 = 10,000.
Increased by a factor of 10^4 or 10,000.