Practice
Give the tainted slice away.
Not zakat. Not a tax deduction you invent. If the holding cannot be screened, do not hold it and purify later as a lifestyle.
£
%
Give the result to charity without intending zakat. If a fund publishes its own purification ratio, use that figure instead of guessing from a 10-K.
Educational, not a fatwa. Structures differ by document and school. Confirm with a qualified scholar before you sign.
To give away
£13.02
3.1% of £420.00 in dividends.