ummm, well... er...; unless there's an invisible decimal point I can't see, parents discussing addition of ONE are not responsive.

If one adds 1 (TEN/TENTHS), of course it evals as the next higher number; the example might be more precise if the discussion were about adding ONE/TENTH, 0.1 or adding FIVE/TENTHS (0.5) save for the fact that it just doesn't work that way:

C:\>perl -e "print (28.6)"
28.6

C:\>perl -e "print (28.1)"
28.1

w2k, This is perl, v5.8.6 built for MSWin32-x86-multi-thread (with 3 registered patches, see perl -V for more detail)