What's the next number? 3 ; 3 ; 5 ; 4 ; 4 ; 3 ; 5 ; 5 ; 4 ; _______?

Answer 1

1234567
o-n-e (3 letters)
t-w-o (3 letters)
t-h-r-e-e (5 letters)
f-o-u-r (4 letters)

Similarly t-e-n has 3 letters
so answer = 3