The official description of Mercer only mentioned that the font size was not less than 12pt, but did not mention the font problem.
Over the years, O-prize papers have various font sizes and different typesetting styles. I think ... this may only show that people's content is so good that the judges ignore typesetting.
The font size of English mathematics test paper is Times New Roman, 1 1pt or 12pt.
. I tried to arrange a few sheets of paper with LaTeX, and I felt that 12pt was still too big.
As there is no standard, I just want to say that I plan to use Times New Roman, 1 1pt this year, including mathematical formulas and appendices.