// source http://jsbin.com/ginoqot

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<head>
  <meta charset="utf-8">
  <title>JS Bin</title>
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// Zero is even.

// One is odd.

// For any other number N, its evenness is the same as N - 2.

// Define a recursive function isEven corresponding to this description. The function should accept a number parameter and return a Boolean.

// Test it on 50 and 75. See how it behaves on -1. Why? Can you think of a way to fix this?

// URL: https://eloquentjavascript.net/03_functions.html#p_iDq2OgBOGw

function isEven(num) {
  
  num = Math.abs(num);
  
  if (num === 0) {
    return true;
  } else if (num === 1) {
    return false;
  }
  
  return isEven(num-2);
  
}

console.log(isEven(50));
console.log(isEven(75));
console.log(isEven(-1));
console.log(isEven(-100));
</script>

// Zero is even.

// One is odd.

// For any other number N, its evenness is the same as N - 2.

// Define a recursive function isEven corresponding to this description. The function should accept a number parameter and return a Boolean.

// Test it on 50 and 75. See how it behaves on -1. Why? Can you think of a way to fix this?

// URL: https://eloquentjavascript.net/03_functions.html#p_iDq2OgBOGw

function isEven(num) {
  
  num = Math.abs(num);
  
  if (num === 0) {
    return true;
  } else if (num === 1) {
    return false;
  }
  
  return isEven(num-2);
  
}

console.log(isEven(50));
console.log(isEven(75));
console.log(isEven(-1));
console.log(isEven(-100));</script></body>
</html>