1225.5, 1225.50, 12255E-1 and 1_225.5 are all stored indentically internally, and
will print them all as 1225.5 because that is how print displays the value 1225.5.
has no idea how the number came to be; it just knows its value. If you wish to preserve the underscores, you want to treat the number as a string instead of as a number, so put quotes around it.