[填空题]
The first three terms of a geometr,3y0q-q9vp l qw0qip5 m7r4emd0g biyic sequence ar* g8eb6. ytidae9 kvdc(3o,yle $u_{1}=0.4, u_{2}=0.6, u_{3}=0.9$a .
1. Find the value of the common ratio, r .≈ !num!2%
2. Find the sum of the first ten terms in the sequence.
3. Find the greatest value of n such that $S_{n}<650$ .
