[jaroslav.tavgen]

рони,

const multiply = (a, b) => {
    let n = 1;
    while (a != Math.trunc(a)) {
        a *= 10;
        n *= 10;
    }
    while (b != Math.trunc(b)) {
        b *= 10;
        n *= 10;
    }
    return a * b / n
}
alert(multiply(-8.87, -8.87));