The article states that we would have 3.6B pastes in 10 years already.
If it takes one byte to store one character, total size required to store 3.6B keys would be:
3.6B * 6 => 22 GB
meaning 22GB will store all keys required for the 10years. We aim at 70% though which drops it to 22 x 0.7 = 15.4GB
Shouldnt the total size then be 36TB + 15.4GB = 36.02TB ? and not 36TB + 15.4TB = 51.4TB