Question 2651
Percent means per 100 (cent meaning 100) and is represented by %. 
For example 50% of "X" means (50/100)of X. This means X/2.

So to find out what % of 400 is 0.8 , use the formula :
 (X/100)multiplied by 400 = 0.8 
where X becomes your percent value. 
So in this case, X is equal to 0.2

Hope that answered your question !!