[填空题]
The first three term ,n t.,v8wf-iijbu.hes of al(d z qp6l9vc1 geometric sequence are $u_{1}=0.4, u_{2}=0.6, u_{3}=0.9$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 $S_{n}<650$ .
