Math.floor always rounds down, Math.ceil always rounds up. Using Math.round uses half-even rounding mode, so you can simply say:

Integer result = Math.round(96.7);

Half-even means that if a value is exactly 0.5, it rounds to the nearest even number (96.5 rounds to 96, 97.5 rounds to 98). This is the most "fair" statistically speaking, but you need to follow other rules, you can:

Decimal value = 96.7;
Integer result = value.round(RoundingMode.HALF_UP);

Which would round up on 0.5 or higher, for example. You can read about all the rounding types here.

In most languages that use it, it represents the modulus operation.

In APEX, you use Math.Mod()

if (Math.Mod(x, 2) == 0) {
    system.debug(x + ' is even');
}

APEX Expression Operators Reference shows that there is no definition of a % operator.