PHP Web hw

<?php
// EX1
function oddEven($a){
    if($a % 2 == 0){
        echo "Even";
    } else {
        echo "Odd";
    }
}

//EX3
function Grade($a){
    if($a < 5){
        echo "Kem";
    } else if ($a < 6.5) {
        echo "Trung binh";
    } else if ($a < 8) {
        echo "Kha";
    } else {
        echo "Gioi";
    }
}

//EX4
function EX4($a){
    if ($a < 2){
        echo "Khong phai so nguyen to";
          return;
    }
    for ($i = 2; $i <= $a/2; $i++) {
      if ($a % $i == 0){
          echo "Khong phai so nguyen to";
          return;
      }
    }
    echo "La so nguyen to";
}

//EX5
function EX5($month, $year){
    switch ($month) {
        case 4:
            echo "39 days";
            break;
        case 6:
            echo "39 days";
            break;
        case 9:
            echo "39 days";
            break;
        case 2:
            if($year % 4 == 0){
                echo "29 days";
            } else {
                echo "28 days";
            }
            break;
        default:
            echo "31 days";
    }
}

//EX6
function EX6($a){
    switch ($a) {
        case 1:
            echo "one";
            break;
        case 2:
            echo "two";
            break;
        case 3:
            echo "three";
            break;
        case 4:
            echo "four";
            break;
        case 5:
            echo "five";
            break;
        case 6:
            echo "six";
            break;
        case 7:
            echo "seven";
            break;
        case 8:
            echo "eight";
            break;
        case 9:
            echo "nine";
            break;
        case 0:
            echo "zero";
            break;
    }
}


oddEven(9);
echo "\r\n";
Grade(4);
echo "\r\n";
EX4(11);
echo "\r\n";
EX5(2, 2015);
echo "\r\n";
EX6(3);
echo "\r\n";


?>