positional notation

NOUN
19 LETTERS · 6 SYLLABLES · STARTS WITH P

positional notation is a valid 19-letter word worth 20 points in Scrabble and 25 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3O1S1I1T1I1O1N1A1L1N1O1T1A1T1I1O1N1
3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 =20 PTS
DOUBLE WORD → 40TRIPLE WORD → 60
MEANING

What does positional notation mean?