The builtΓÇôin features of Scheme are in any case not powerful enough to support such conventions: You can specify that a number is exact or inexact, for example with the "#e" and "#i" prefixes, but Scheme records only that one bit of information. There is no builtΓÇôin means to tell Scheme how many digits of precision the number has. As far as input to Scheme is concerned, the strings "1.50000" and "1.5" indicate the same number and the same status of the "exact bit". (In the case of Pixie Scheme, that number is the inexact rational 1.5.)