 # Explanation lesson Built-in Objects semantics problem

In the lesson Built-in Objects I do not understand the highlighted part, I suppose it includes the zero and excludes the one because it appears adjacently respectively within brackets inclusive and exclusive regarding zero and one, that’s right? Also, evaluate means mathematically belonging to the same equivalence class or it means finding a numerical expression? 1. Since we’re in the world between 0 and 1, you are correct: It will generate a random decimal between 0 (which could be 0 - inclusive), and 1 (which can’t be 1 - exclusive). So if we look at it as percentages `.random()*100`, you can have 0% thru 99%, but not 100%.

2. Which function is this in reference to? In this case, it appears to mean the same as `return`: It will likely output a decimal.

I updated, so it means output?

In this case, yes. Math.random() by default outputs a decimal between 0 and 1, so when it’s multiplied, it often remains a decimal unless rounded (as they suggest here).