diff --git a/_concepts.txt b/_concepts.txt
index e0dd1bc..6ec2437 100644
--- a/_concepts.txt
+++ b/_concepts.txt
@@ -69,12 +69,11 @@ def concept ninety as 90
 ninety isa number
 def concept nineties from bnf ninety number where number < 10 as ninety + number
 nineties isa number
-# def concept hundreds1 from number 'hundred' where number < 10 as number * 100
-# def concept hundreds2 from number=number1 'hundred' 'and' number=number2 where number1 < 10 and number2 < 100 as number1 * 100 + number2
 def concept one hundred as 100
 one hundred isa number
-# hundreds1 isa number
-# hundreds2 isa number
+def concept hundreds from bnf number=n1 'hundred' 'and' number=n2 where n1 < 10 and n2 < 100 as n1 * 100 + n2
+hundreds isa number
+#def concept hundreds from bnf number 'hundred' where number < 10 as number * 100
 def concept thousands from bnf number 'thousand' where number < 1000 as number * 1000
 thousands isa number
 def concept history as history()