//1. Powerful Cars.
function convertKWtoHP(value) {
    return Number(value/ 0.745699872).toFixed(2);
}

//2. Rounding Numbers.
function roundNumber(value){
    return Math.floor(value)+"\n" + Math.round(value);
}
//3. Even Numbers.
function evenNumber(value){
   return value % 2 == 0;
}
//4.Prime Numbers.
function isPrime(value) {
    var primes = [2, 3, 5, 7];
    for (var i = 0; i < primes.length; i++) {
        if ((value != primes[i])&& value % primes[i] == 0) {
           return false;
        }
        else {
            if (i == primes.length - 1) {
                return true;
            }
        }
    }
}
//5.Divide by 3.
function divisionBy3(value){
    var newV = value.toString();
    var result = '';
    for (var i = 0; i < newV.length; i++) {
        result += newV[i];
    }
    if (result % 3 == 0) {
        return "the number is divided by 3 without remainder";
    }
    else {
        return "the number is NOT divided by 3 without remainder";
    }
}
//6. Checking Bits.
function bitChecker(value) {
    return (value & 8) > 0;
}
//7. Lifetime Supply Calc.
function calcSupply(age,maxAge,foodAmount) {
    var totalFood = ((maxAge - age) * foodAmount) * 365;
    return totalFood +"kg of meat would be enough until I am " +maxAge + " years old." ;
}
//8. Cylinder Volume.
function calcCylinderVol(radius,height) {
    var volume =  Math.PI * Math.pow(radius,2) * height;
    return volume.toFixed(3);
}
//9.Tree House.
function treeHouseCompare(a, b) {
    function radHeight(v) {
        return ((v / 3) * 2);
    }

    var houseArea = (a * a) + (a / 2 * radHeight(a));
    var treeArea = b * (b / 3) + (Math.PI * Math.pow(radHeight(b), 2));
    return (houseArea > treeArea) ? "house/" + houseArea.toFixed(2) : "tree/" + treeArea.toFixed(2);
}
//10. Digit Checker.
function checkDigit(value){
    var val = value.toString();
    return val[val.length - 3] == 3;
}
//11. Digit As Word.
function convertDigitToWord(value) {
    switch(Number(value)){
        case 1 : return "one"; break;
        case 2 : return "two"; break;
        case 3 : return "three"; break;
        case 4 : return "four"; break;
        case 5 : return "five"; break;
        case 6 : return "six"; break;
        case 7 : return "seven"; break;
        case 8 : return "eight"; break;
        case 9 : return "nine"; break;
    }
}
//12. Variables.
function variablesTypes(value){
    return "My name is " + value[0] + " //type is " + typeof(value[0])+"\n"
        + "My age is " + value[1] + " //type is " + typeof(value[1])+"\n"
        + "I am " + isMale(value[2]) + " //type is " + typeof(value[2])+"\n"
        + "My favorite foods are: " + value[3] + " //type is " + typeof(value[3]);
    function isMale(gender){
        return gender ? "Male" : "Female";
    }
}