Respuesta :
All of the numbers are being put with how many letters are in the word.
For example 19=8: N I N E T E E N & 6=3: S I X, etc.
So if we have 16=? and 17=?...
16 would be 7 because there are 7 letters in the word:
S I X T E E N.
17 would be 9 because there are 9 letters in the spelling of the word:
S E V E N T E E N.
I hope this helped.~