7 Expressions [expr]

7.6 Compound expressions [expr.compound]

7.6.5 Multiplicative operators [expr.mul]

The multiplicative operators *, /, and % group left-to-right.
The operands of * and / shall have arithmetic or unscoped enumeration type; the operands of % shall have integral or unscoped enumeration type.
The usual arithmetic conversions are performed on the operands and determine the type of the result.
The binary * operator indicates multiplication.
The binary / operator yields the quotient, and the binary % operator yields the remainder from the division of the first expression by the second.
If the second operand of / or % is zero the behavior is undefined.
For integral operands the / operator yields the algebraic quotient with any fractional part discarded;79 if the quotient a/b is representable in the type of the result, (a/b)*b + a%b is equal to a; otherwise, the behavior of both a/b and a%b is undefined.
This is often called truncation towards zero.