US Social Security information

I am nearly 70 years old and needing to submit a self assessment tax return for the first time. This is because I now also receive some payments from the US Social Security system. These need to be submitted on the Foreign Pages. These payments arrive monthly and are each month converted from US$ to UK£, with fluctuating rates. QUESTION 1: In figuring out what figure to submit in the "Overseas pensions., social security benefits & royalties" box in Column B for much I have received during 2022/2023, do I (a) add up all the 12 UK£ payments relevant to the UK tax year and *then* rundown to the nearest pound OR do I round *each* of the 12 discrete/different monthly payment down to the nearest pound and *then* add up these figures to come to a total figure? QUESTION 2 The figure for Column B is £0. I have no idea what any of the words mean for Columns D & E. So I am going to Just deduct £0 from whatever you tell me should go into Column B - is that right?

Corrected QUESTION 2 : The figure for Column C is £0. I have no idea what any of the words mean for Columns D & E. So, to complete column F, I am going to Just deduct £0 from whatever you tell me should go into Column B. Is that right?

Hi

On page F2 of SA106, you would enter the gross amount of US pension paid in column 'B' in pounds sterling.  
If you have received a document from the pension provider, advising how much pension was paid in the US tax year (1 Jan to 31 Dec) please enter this is box 'B' in pounds sterling.  
As you have not paid tax on the pension in the US, you can leave boxes 'C','D' & 'E' blank.

Thank you