When doing the devision in IRB:
6/3600
the result is always 0.
But in a live Rails application running in WEBrick or Apache/Passenger the same division results in 1/600 value of type Rational.
I am getting the same Rational result when doing division in a breakpoint's watch in RubyMine 6.3.3
Both arguments are always Integer.
This has to do with the mathn module. For some reason it's not loaded in your IRB, but it's loaded by something in your server session and probably from a debugging gem in the RubyMine debug session as well.
The behaviour you experienced is documented here: http://www.ruby-doc.org/stdlib-2.1.1/libdoc/mathn/rdoc/Numeric.html
You can test this in your IRB session. 6/3600 results in 0. After you loaded mathn with require 'mathn' you get another result. It will be (1/600) instead.
You can also force each situation, to make your code more robust at this point. If you want a rational result anyway you can do something like 6/3600.to_r or vice versa if mathn is loaded (6/3600).to_i. Another way to make a division explicit is to use the method div().
Here a dump of an IRB session, which is a conclusion of the text above.
>> 6/3600
0
>> 6/3600.to_r
(1/600)
>> require 'mathn'
true
>> 6/3600
(1/600)
>> (6/3600).to_i
0
>> 6.div(3600)
0
This topic is also discussed here: https://bugs.ruby-lang.org/issues/2121