### Question:
RecursionExample { public int powerOf10(int n){ if (n == 0){ return 1; } return powerOf10(n-1)*10; }  int sum(int n); int tailSum(int currentSum, int n); int iterativeSum(int n); int powerOf10(int n); int fibonacci(int n); String toBinary(int n); int calculateTreeHeight(BinaryNode root); int max(int a,int b);  }### Answer:
@Test public void testPowerOf10() { int p0 = recursion.powerOf10(0); int p1 = recursion.powerOf10(1); int p4 = recursion.powerOf10(4); Assert.assertEquals(1, p0); Assert.assertEquals(10, p1); Assert.assertEquals(10000, p4); }