Sir now as there will be 20 professional marks, so is it necessary to use spreadsheet formulas? If we do not use spreadsheet formulas and instead do calculation on manual calculator, then will professional marks be deducted for it?
No, marks are not deducted if you do the calculations on a calculator.
However it is better to use the spreadsheet functions because it is faster. Also marks are given for workings so if you use a calculator you need to write down what you have done. When you use the spreadsheet you do not need to write down because the marker is able to see the spreadsheet functions that you have used.