**Numbers : A binary number is written as a bit string followed by the letter "B" or "b"; for example, 1010B
A decimal number must begin with a decimal digit and end with the letter "H" or "h"; For Example, 0ABCH (the reason for this is that the assembler would be unable to tell whether a symbol such as "ABCH" represents the variable name "ABCH" or the hex number ABC).
Any of the preceding numbers may have an optional sign. Here are examples of legal and illegal numbers for MASM.
1,234 illegal-contains a nondigit character hex
1B4DH illegal hex number-doesn't end in "H"
1B4D illegal hex number -doesn't begin with
FFFFH a decimal digit