1. Find the factorial of a given number (review) Factorial definition: 5 factorial = 5! = 5 * 4 * 3 * 2 * 1 = 120
2. Print out all elements in an array recursively
3. Concatenate all the elements in an array of Strings Sample Input: ["Hi", "there", ",", " ", "user","!"] Sample Output: "Hi there, user!"
4. Find the sum of all the numbers in an array Sample Input: [3,6,1,3,2] Sample Output: 15
5. Find the sum of all the even numbers in an array Sample Input: [3,6,1,3,2, 10] Sample Output: 18
6. Multiply two given Ints. Do not use for/while loops or the * operator. Sample Input: 5 * 6 Sample Output: 30
7. Write a recursive function pow that takes two numbers x and y as input and returns x to the power y. Do not use for/while loops Sample Input: 3 ^ 4 Sample Output: 81