split numbers

i have to create a number from a 18 digit number the math is simple and so is getting the result this is how i do it
i have a 18 digit number like this
982613530890001448
then i split the number like this using the text to columns command in excel
so i get this result in many columns
9 8 2 6 1 3 5 3 0 8 9 0 0 0 1 4 4 8
then i have to multiply every second number by 2 like this
8*2 6*2 3*2 3*2 8*2 0*2 0*2 4*2 8*2
this gives me this result
16 12 6 6 16 0 0 8 16
then i split each one these numbers into two like this
1 6 1 2 6 6 1 6 0 0 8 1 6
then i add all these numbers together and the remaining numbers that havent been doubled together to get a figure like 76 then round up to nearest ten then subtract 76 from 80 to get my final figure then i have a nineteendigit number like this
9826135308900014485 4
this is the number i need i can do it in one field using data i input but how can i doit over multiple fields so that i can copy the last seven digits from a excel spreadsheet into this one and create a list of numbers including the last figure using my unique formula

please help me

Excel stored number to an accuracy of 15 didgets. If you want to deal with nineteen didgit numbers, you'l have to work with numerals (strings) rather than with numbers.

Use MID function, instead of text to columns to separate it (you need to enter 19 (or as the case may be) times to get the result and you can individually put nested formulae in the functions. Forward the sheet, if you want to have the exact solution.