Below you can find links to past papers for the Edexcel IGCSE A in Mathematics. The Old Syllabus papers continue to be relevant, though the new syllabus papers have a few new topics and some harder questions.
I have also made documents with past paper questions by topic as well as some mixed harder problems, most of which also have video solutions.
New Syllabus (9-1)
The Casio fx-991 is the calculator I would recommend for GCSE and IGCSE examinations. You can buy it here or read more detail about this and other calculators in my complete guide to buying the right calculator for school mathematics.