From: Derek Teixeira <derek.teixeira@...>
Date: 2007-02-19T02:31:14+09:00
Subject: Re: modulus/division..

Timothy Hunter wrote:
> Derek Teixeira wrote:
>> puts 4%5
>>
>> and for everyline i got "4" as the remainder.. but when i tried these 
>> with a calulator .. i only got 4 as a remainder for the 1000. when i did 
>> the 4/500 i got a .008 .. so shouldn't the % be an 8?
>>
>>   
> When I was in elementary school they taught us these words for division.
> Suppose you have 9 divided by 4. 4 is the "divisor". 9 is the
> "dividend". 4 goes into 9 2 times, so 2 is the "quotient", but since 4
> times 2 is only 8, there is 1 left over. 1 is called the "remainder".
> The modulus operator returns the remainder after dividing two integers.
> That is, 9 % 4 = 1.
> 
> So what is 4 % 5? 5 goes into 4 0 times. 0 times 5 is 0, so there is 4
> left over. 4 % 5 = 4. For 4 % 10, 10 goes into 4  0 times, with 4 left
> over. 4 % 10 = 4. Same for 4 % 50 and all your other examples.
> 
> For interesting experiments, use a divisor that is smaller than the
> dividend. 10 % 4 = 2. 12 % 3 = 0.
> 
> For more interesting experiments, use negative numbers.

i think i've got it!

is this pretty mcuh what they are saying .. i put explanations next to 
each line ..
def old_roman_number input

  while input < 1 || input > 3999
    puts 'Please enter a number between 1 and 3999'
    input = gets.chomp.to_i
  end

  m_mod = input%1000  4/1000 means 1000 goes into 4 zero times so 0*1000 
= 0 .. so 4-0= 4
  d_mod = input%500   4/500 means  500 goes into 4 zero times 0* 500 = 0 
... so 4-0=4
  c_mod = input%100   4/100 means 100 goes into 4 zero times 0*100 =0 .. 
so 4-0=4
  l_mod = input%50    4/50 means 50 goes into 4 zero times 0*50 = 0 .. 
so 4-0=4
  x_mod = input%10    4/10 means 10 goes into 4 zero times 0*10 = 0 .. 
so 4-0 = 4
  v_mod = input%5     4/5 means 5 goes into 4 zero time 0*5 = 0 .. so 
4-0= 4

  m_div = input/1000  = 4/1000 = 0
  d_div = m_mod/500   = 4/500 = 0
  c_div = d_mod/100   = 4/100 = 0
  l_div = c_mod/50   = 4/50 = 0
  x_div = l_mod/10   = 4/10 = 0
  v_div = x_mod/5   = 4/5 = 0
  i_div = v_mod/1   = 4/1=4

  m = 'M' * m_div = 0
  d = 'D' * d_div = 0
  c = 'C' * c_div = 0
  l = 'L' * l_div = 0
  x = 'X' * x_div = 0
  v = 'V' * v_div = 0
  i = 'I' * i_div = 4 * I equals IIII

  puts m + d + c + l + x + v + i

end

number = gets.chomp.to_i
old_roman_number(number)

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