From: Fily Salas <fs_tigre@...>
Date: 2011-11-04T23:13:49+09:00
Subject: I need help understanding this small piece of code

Hi,

I have been trying to understand some code found in the "Learn to
Program" book and I'm having a hard time understanding it, I don't know
if its because I don't know math (which is true) or I don't simply
understand
how Ruby is interpreting the code.

//def old_roman_numeral (num)
///////  roman = ''
///////  roman = roman + 'M' * (num / 1000)
///////  roman = roman + 'D' * (num % 1000 / 500)
///////  roman = roman + 'C' * (num % 500 / 100)
///////  roman = roman + 'L' * (num % 100 / 50)
///////  roman = roman + 'X' * (num % 50 / 10)
///////  roman = roman + 'V' * (num % 10 / 5)
///////  roman = roman + 'I' * (num % 5 / 1)
///////  return roman
//end


puts(old_roman_numeral(1999))


What I don't know understand are the expressions surrounded with
parenthesis "(num % 1000 / 500) etc"
I do understand that we are passing a parameter when calling the method
and then multiplying the roman letters by this number passed as argument
but, what is... '(num % 1000 / 500)' = WHAT?

("number" "percentage"  1000 / 500) = WHAT?

Can someone be so kind and explain this a little bit?  I know this may
be my math but I don’t see (num % 1000 / 500) being a math equation.

Thanks

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