There is no need to use the new Roman font to represent the percentage of 27%, because percentage is a mathematical or statistical term and has nothing to do with font. 27% can be directly represented by Arabic numerals and percentage signs, such as "27%". If you need to use some specific fonts when writing a paper, you should follow the principle that the selected fonts are suitable for what you write. However, when expressing percentages, the choice of font is not necessary.