First find out the rules, then fill in the numbers (1)1,1.1,1.3,1.6,( ),( ),3.1,( ).

First find out the rules, then fill in the numbers (1)1,1.1,1.3,1.6,( ),( ),3.1,( ).

Add 0.1 more each time to the difference between the two numbers
(1)1,1.1,1.3,1.6,( 2.0 ),( 2.5 ),3.1,( 3.8 ).