Dear Asim,
If you would like to use the rpt 1404 amount to text methods, you need to copy the following functions, variables into your process.
functions, do you need:
Name
FormatNoText - this is convert your number to Text
AddToNoText - this is build the ones, tens, hundreds, exponents, etc
InitTextVariable - this is need to run at the beginning, this function is get the Text constants into your variables
variables do you need:
Name DataType Subtype Length
OnesText Text 30
TensText Text 30
ExponentText Text 30
DescriptionLine Text 80 - dimension 2
Do you neeed the Text Constants to copy:
From Text026 to Text029, Text032 to Text061. As you can see, these are the Text of your numbers.
When you implement these into your solutions, you can call them for example like this:
In a codeunit, OnRun() method:
InitTextVariable;
FormatNoText(DescriptionLine,256.45,‘EUR’);
MESSAGE(DescriptionLine[1]);
In Summary, the FormatNoText is checking how many ones, tens, hundreds do you have and calling the AddToNoText to build them together.
I tried to explain it clear, but it is more complex. It is math 
Rgds,
A