PrecedenceForm[expr, prec] prints with expr parenthesized as it would be if it contained an operator with precedence prec.
prec must be an integer. See notes for Infix.
Example: a + PrecedenceForm[b c, 10] .
PrecedenceForm acts as a "wrapper", which affects printing, but not evaluation.
See The Mathematica Book: Section 2.8.16.