Question

in application.helper I was trying to do this.
However it always get 0. Why?

I want something like 37% 49% 98%
Always integer. no float

def evaluate(number_of_people)
    percentage = ((number_of_people / 10000) * 100 ).truncate
    "<div class='percentage'>Percentage is #{percentage}%</div>".html_safe
end

Answer 1

You’re dividing by an integer, so the result of 3000 / 10000 will be 0.

Divide by 10000.0 instead to force decimal aritmatic.

So change this:

percentage = ((number_of_people / 10000) * 100 ).truncate

To this:

percentage = ((number_of_people / 10000.0) * 100 ).to_i

If your denominator (the 10000 value in this case) is a variable you can use to_f to cast it as a float before dividing.