diff --git a/lib/census_api.rb b/lib/census_api.rb
index 19381c16a..559a6388e 100644
--- a/lib/census_api.rb
+++ b/lib/census_api.rb
@@ -15,36 +15,13 @@ class CensusApi
     variants = []
 
     if is_dni?(document_type)
-      # If a letter exists at the end, delete it and put it on the letter var
-      letter = document_number.last
-      if letter[/[A-Za-z]/] == letter
-        document_number = document_number[0..-2]
-      else
-        letter = nil
-      end
+      document_number, letter = split_letter_from(document_number)
+      number_variants = get_number_variants_with_leading_zeroes_from(document_number)
+      letter_variants = get_letter_variants(number_variants, letter)
 
-      document_number = document_number.last(8) # Keep only the last x digits
-      document_number = document_number.gsub(/^0+/, '') # Removes leading zeros
-
-      # if the number has less digits than it should, pad with zeros to the left and add each variant to the list
-      # For example, if the initial document_number is 1234, possible numbers should have
-      # [1234, 01234, 001234, 0001234]
-      possible_numbers = []
-      possible_numbers << document_number unless document_number.blank?
-      while document_number.size < 8
-        document_number = "0#{document_number}"
-        possible_numbers << document_number
-      end
-
-      variants += possible_numbers
-
-      # if a letter was given, try the numbers followed by the letter in upper and lowercase
-      if letter.present? then
-        possible_numbers.each do |number|
-          variants << number + letter.downcase << number + letter.upcase
-        end
-      end
-    else # not a DNI
+      variants += number_variants
+      variants += letter_variants
+    else # if not a DNI, just use the document_number, with no variants
       variants << document_number
     end
 
@@ -111,4 +88,43 @@ class CensusApi
     def is_dni?(document_type)
       document_type.to_s == "1"
     end
+
+    def split_letter_from(document_number)
+      letter = document_number.last
+      if letter[/[A-Za-z]/] == letter
+        document_number = document_number[0..-2]
+      else
+        letter = nil
+      end
+      return document_number, letter
+    end
+
+    # if the number has less digits than it should, pad with zeros to the left and add each variant to the list
+    # For example, if the initial document_number is 1234, and digits=8, the result is
+    # ['1234', '01234', '001234', '0001234']
+    def get_number_variants_with_leading_zeroes_from(document_number, digits=8)
+      document_number = document_number.to_s.last(digits) # Keep only the last x digits
+      document_number = document_number.gsub(/^0+/, '')   # Removes leading zeros
+
+      variants = []
+      variants << document_number unless document_number.blank?
+      while document_number.size < digits
+        document_number = "0#{document_number}"
+        variants << document_number
+      end
+      variants
+    end
+
+    # Generates uppercase and lowercase variants of a series of numbers, if the letter is present
+    # If number_variants == ['1234', '01234'] & letter == 'A', the result is
+    # ['1234a', '1234A', '01234a', '01234A']
+    def get_letter_variants(number_variants, letter)
+      variants = []
+      if letter.present? then
+        number_variants.each do |number|
+          variants << number + letter.downcase << number + letter.upcase
+        end
+      end
+      variants
+    end
 end