Find the rule 6.25 2.5 1 () ()

Find the rule 6.25 2.5 1 () ()

The difference between two adjacent numbers is 2.5 times,
6.25/2.5=2.5,2.5/2.5=1;1/2.5=0.4
0.4/2.5=0.16
The answers are 0.4 0.16