Question

What number is between 0.01 and 0.1??

Answer 1

There are an infinite number of those.
A few of them are ...

0.01000000000000001
0.02
0.03
0.04
0.045
0.05
0.055
0.06
0.07
0.08
0.081
0.082
0.089
0.09
0.091
0.09100001
0.0910000100001
0.09100002
0.098
0.099
0.0999
0.09999
0.099991
0.099992
0.0999999999999999999999999
.
.
etc.

If you just want the number that's exactly in the middle
between  0.01  and  0.1 , then that's called the "average"
of  0.01  and  0.1 .

To find the average of any list of items ...
-- add them all up
-- divide their sum by the number of items on the list.

Your list has only two items on it.

-- Add them up . . . . . (0.01 + 0.1) =  0.11
 
-- Divide the sum by
   the number of items on the list:  0.11 / 2  =  0.055 .

Answer 2

Any number like 0.01 0.02 0.03 and so on to 0.09