Hi John - the comment for Number class>>readFrom: states
"Any numbers in the stream are expected to obey Smalltalk syntax rather than any locale specific formatting, i.e. this is not intended for reading user input."
...so bearing this in mind the error is correct since +7 is not valid Smalltalk syntax.
I thought that the NumberToText class would handle your scenario since it's part of the MVP framework and thus potentially user-facing. However it also uses Number class>>readFrom: and so has the same problem (though it does at least have a #todo comment on the reverse conversion saying "...should use GetNumberFormat() to produce locale specific output").