numeration system

NOUN
17 LETTERS · STARTS WITH N

numeration system is a valid 17-letter word worth 23 points in Scrabble and 27 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
N1U1M3E1R1A1T1I1O1N1S1Y4S1T1E1M3
1 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 4 + 1 + 1 + 1 + 3 =23 PTS
DOUBLE WORD → 46TRIPLE WORD → 69
MEANING

What does numeration system mean?