JavaScript - Generating divisions in halves

I have the following JavaScript code:

var expressionBuilder = function() {
    var firstNumber = getRandomInt(1, 10);
    var secondNumber = getRandomInt(1, 10);
    var operand = getRandomOperator();

    if (operand === '-') {
        do {
            firstNumber = getRandomInt(1, 10);
            secondNumber = getRandomInt(1, 10);     
        } while (firstNumber < secondNumber);
    }

    if (operand === '/') {
        do {
            firstNumber = getRandomInt(1, 10);
            secondNumber = getRandomInt(1, 10);     
        } while (firstNumber < secondNumber && ((firstNumber / secondNumber) % 0.5) != 0);
    }

    return firstNumber + ' ' + operand + ' ' + secondNumber;
};

Which is pretty self explanatory. The division bit was suppose to generate numbers such that I would only get division results like 0.5, 1, 1.5 etc:

((firstNumber / secondNumber) % 0.5) != 0

Divisible by 1/2 that is. However, I still get expressions like 8/7. Why?