Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: Himself - President & Co-Founder, The Breakthrough Institute:  When we look at nuclear we have to understand that we 're making a long term investment .
Himself - President & Co-Founder, The Breakthrough Institute: Now it 's a big upfront capital cost , but these are plants that are going to last _ 60 _ , 80 , maybe even 100 years .

years