What is a number between 5.65 and 5.66?

The mid point number is

(5.65 + 5.66) / 2 =

11.31/2 =

5.655 is a number between the two given numbers.

Other numbers would be

5,651, 5.652, 5.653, 5.654, 5.656, 5.657, 5.658, 5.569

To reduce the decimals even further but still between the given limits. , we could have

5.6501, 5.6502 et.seq.,