Pedro30

I sold my shares for around £4,900 on 5th April which comes under the 23/24 tax year. I understand the annual exempt amount for individuals is £6000. I have two questions: 1. As i do self assessment do i need to declare the share sales as it comes well under the exempt amount and this is the only transaction I made in the 23/24 year that is a capital gain? 2. If i do need to declare it on my self assessment, i know how much the shares sold for though i don't know the exact amount i bought it for as during the 30 years of holding onto them any dividend received was reinvested in purchasing more shares, can you please advise? Thank you