 Fixed-form Fortran ignores whitespace (in all contexts), so 700 000 000 is permissible.C++14, Rebol, and Red allow the use of an apostrophe for digit grouping, so 700'000'000 is permissible.The International Bureau of Weights and Measures states that "when there are only four digits before or after the decimal marker, it is customary not to use a space to isolate a single digit".