Hello Rohan, of course you could write as n2 for 2n. But some times we n2 with suffix. So n2 could be mistaken as that one. So we also prefer writing numeral first and alphabet following it. 3 apples, 6 roses, 15 horses, same way 46 a , 54 a b^2 ,
233 a^3 b^3. Hope you have felt the convenience of writing so