I'm trying to take user's input for their birthday and break it down to
a single digit through multiple addition formulas. Example...

03+22+1983=2008
2 + 0 + 0 + 8 =10
1 + 0 = 1

irb:

2.1.1 :001 > month = gets.chomp.to_f
=> 3.0
2.1.1 :002 > day = gets.chomp.to_f
=> 22.0
2.1.1 :003 > year = gets.chomp.to_f
=> 1983.0
2.1.1 :004 > birth = (month+day+year).to_i
=> 2008

That is as far as I've gotten. I can't break the 2008 to get to the
next step in the formula. Any suggestions?