diff --git a/app/arrays.js b/app/arrays.js
index 5e3fdce..666215a 100644
--- a/app/arrays.js
+++ b/app/arrays.js
@@ -16,6 +16,11 @@ exports.arraysAnswers = {
   },
 
   sum : function(arr) {
+    
+    /*
+    if (Array.prototype.reduce) { return arr.reduce( (base, el) => base + el, 0); }
+    */
+    
     var sum = 0;
 
     for (var i = 0, len = arr.length; i < len; i++) {
@@ -26,6 +31,11 @@ exports.arraysAnswers = {
   },
 
   remove : function(arr, item) {
+    
+    /*
+    if (Array.prototype.filter) { return arr.filter((el) => !(el === item)); }
+    */
+    
     var ret = [];
 
     for (var i = 0, len = arr.length; i < len; i++) {
@@ -38,6 +48,16 @@ exports.arraysAnswers = {
   },
 
   removeWithoutCopy : function(arr, item) {
+    
+    /*
+    for ( var pos = arr.indexOf(item)
+      ; pos > -1
+      ; pos = arr.indexOf(item)) {
+      arr.splice(pos, 1);
+    }
+    return arr;
+    */
+    
     var i, len;
 
     for (i = 0, len = arr.length; i < len; i++) {
@@ -81,6 +101,14 @@ exports.arraysAnswers = {
   },
 
   count : function(arr, item) {
+    
+    /*
+    if (Array.prototype.reduce) {
+      return arr.reduce((base, el) => base + (el === item ? 1 : 0)
+        , 0);
+    }
+    */
+    
     var count = 0;
 
     for (var i = 0, len = arr.length; i < len; i++) {
@@ -93,6 +121,18 @@ exports.arraysAnswers = {
   },
 
   duplicates : function(arr) {
+    
+    /*
+    var seen = new Set([]),
+      dupes = new Set([]);
+    arr.forEach(el => {
+      if (seen.has(el)) {dupes.add(el);}
+      seen.add(el);
+    }
+    );
+    return Array.from(dupes);
+    */
+    
     var seen = {};
     var dupes = [];
 
@@ -110,6 +150,13 @@ exports.arraysAnswers = {
   },
 
   square : function(arr) {
+    
+    /*
+    if (Array.prototype.map) {
+      return arr.map(el => el * el);
+    }
+    */
+    
     var ret = [];
 
     for (var i = 0, len = arr.length; i < len; i++) {
diff --git a/app/async.js b/app/async.js
index a3a0bbd..7c9e33e 100644
--- a/app/async.js
+++ b/app/async.js
@@ -1,7 +1,13 @@
 exports = (typeof window === 'undefined') ? global : window;
 
 exports.asyncAnswers = {
+  
   async : function(value) {
+    
+    /* does not use jQuery
+    return new Promise((resolve, reject) => setTimeout(() => resolve(value), 10));
+    */
+    
     var dfd = $.Deferred();
     setTimeout(function() {
       dfd.resolve(value);
diff --git a/app/flowControl.js b/app/flowControl.js
index 67dcda6..998cb85 100644
--- a/app/flowControl.js
+++ b/app/flowControl.js
@@ -21,7 +21,7 @@ exports.flowControlAnswers = {
     // if the number is divisible by 3 AND 5, then when divided by both,
     // the remainder for each operation will be zero
     // return 'fizzbuzz'
-    if (num % 3 === 0 && num % 5 === 0) {
+    if (num % (3*5) === 0) {
       return 'fizzbuzz';
     }
 
diff --git a/app/functions.js b/app/functions.js
index 2f0249d..c9dd125 100644
--- a/app/functions.js
+++ b/app/functions.js
@@ -1,11 +1,19 @@
+purge
+
 exports = (typeof window === 'undefined') ? global : window;
 
 exports.functionsAnswers = {
   argsAsArray : function(fn, arr) {
+    /*
+        return fn(...arr);
+    */
     return fn.apply(null, arr);
   },
 
   speak : function(fn, obj) {
+    /*
+        return fn.bind(obj)();
+    */
     return fn.call(obj);
   },
 
@@ -16,6 +24,15 @@ exports.functionsAnswers = {
   },
 
   makeClosures : function(arr, fn) {
+    
+    /*
+    if (Array.prototype.map) {
+      return arr.map(function (el) {
+        return function () {return fn(el);};
+      });
+    }
+    */
+    
     var ret = [];
 
     var makeFn = function(val) {
@@ -34,6 +51,14 @@ exports.functionsAnswers = {
       return fn.call(null, str1, str2, str3);
     };
   },
+  
+  /*
+  useArguments: function (...ar) {
+    if (Array.prototype.reduce) {
+      return ar.reduce((el, base) => el + base);
+    }
+  },
+  */
 
   useArguments : function() {
     var sum = 0;
@@ -45,10 +70,24 @@ exports.functionsAnswers = {
     return sum;
   },
 
+  /*
+  callIt: function (fn, ...ar) {
+    return fn(...ar);
+  },
+  */
+  
   callIt : function(fn) {
     var args = Array.prototype.slice.call(arguments, 1, arguments.length);
     fn.apply(null, args);
   },
+  
+  /*
+  partialUsingArguments: function (fn, ...ar) {
+    return function (...br) {
+      return fn(...ar, ...br);
+    };
+  },
+  */
 
   partialUsingArguments : function(fn) {
     var args = Array.prototype.slice.call(arguments, 1, arguments.length);
@@ -59,6 +98,23 @@ exports.functionsAnswers = {
   },
 
   curryIt : function(fn) {
+    
+    /*
+    var allargs = [],
+      funcLen = fn.length;
+
+    var f = function (newarg) {
+      if (newarg !== undefined && newarg != null) {
+        allargs.push(newarg);
+        if (allargs.length >= funcLen) {
+          return fn(...allargs);
+        }
+      }
+      return f;
+    };
+    return f(null);
+   */
+   
     function applyArguments(fn, arguments) {
       return fn.apply(null, arguments);
     }
diff --git a/app/recursion.js b/app/recursion.js
index 27d4b32..e5e7f3e 100644
--- a/app/recursion.js
+++ b/app/recursion.js
@@ -1,7 +1,27 @@
 exports = (typeof window === 'undefined') ? global : window;
 
 exports.recursionAnswers  = {
+  
   listFiles: function(data, dirName) {
+    
+    /*
+   // thisdir: does the dir of the data contribute to the answer?
+    var thisdir = (dir === undefined) || (dir === null) || (data.dir === dir),
+      rslt = [],
+      elval;
+    for ( var el in data.files) {
+      // elements in 'files' (elval) can be filename (a string) or object
+      elval = data.files[el];
+      if (typeof elval === 'string') {
+        if (thisdir) { rslt.push(elval); }
+      } else {
+        // recursion
+        rslt = rslt.concat(this.listFiles(elval, thisdir ? elval.dir : dir));
+      }
+    }
+    return rslt;
+    */
+    
     var listOfFiles = [];
     var dirs = [];
 
@@ -72,5 +92,41 @@ exports.recursionAnswers  = {
         temp.slice()
       );
     }
+  },
+  
+  fibonacci: function (n) {
+    // a is the previous-previous number in the series
+    // b is the previous number (latest) in the series
+    // q is which number in the series to return
+    var fib = function (a, b, q) {
+      if (q === 0) { return a; }
+      if (q === 1) { return b; }
+      // recursion
+      return fib(b, a + b, q - 1);
+    };
+    return fib(0, 1, n);
+  },
+  
+  validParentheses: function (n) {
+    var vParens = function (nInPar, nOutPar) {
+      var result = [];
+      var theRest = [];
+      // terminal case
+      if (nOutPar === 0) { return ['']; }
+      if (nInPar > 0) {
+        // can output '('
+        // recursion
+        theRest = vParens(nInPar - 1, nOutPar);
+        theRest.forEach((el) => result.push('('.concat(el)));
+      }
+      if (nOutPar > nInPar) {
+        // can output ')'
+        // recursion
+        theRest = vParens(nInPar, nOutPar - 1);
+        theRest.forEach((el) => result.push(')'.concat(el)));
+      }
+      return result;
+    };
+    return vParens(n, n);
   }
 };
diff --git a/app/strings.js b/app/strings.js
new file mode 100644
index 0000000..40e67f8
--- /dev/null
+++ b/app/strings.js
@@ -0,0 +1,47 @@
+exports = (typeof window === 'undefined') ? global : window;
+
+exports.stringsAnswers = {
+  reduceString: function (str, amount) {
+    var track = { char: '', cnt: 0 };
+    var rsltArray = str.split('').filter(function (el) {
+      if (el === track.char) {
+        if (track.cnt < amount) {
+          track.cnt++;
+          return true;
+        } else { return false; }
+      } else {
+        track = { char: el, cnt: 1 };
+        return true;
+      }
+    }
+    );
+    return rsltArray.join('');
+  },
+
+  wordWrap: function (str, cols) {
+    var colCnt = 0,
+      currWord,
+      i,
+      prevWord,
+      resultArray = [],
+      wordArray = str.split(/\s/),
+      wordArrayLen = wordArray.length;
+    prevWord = wordArray[0];
+    for (i = 1; i < wordArrayLen; i++, prevWord = currWord) {
+      currWord = wordArray[i];
+      if ((colCnt + prevWord.length + currWord.length + 1) <= cols) {
+        resultArray.push(prevWord + ' ');
+        colCnt += prevWord.length + 1;
+      } else {
+        resultArray.push(prevWord + '\n');
+        colCnt = 0;
+      }
+    }
+    resultArray.push(prevWord);
+    return resultArray.join('');
+  },
+
+  reverseString: function (str) {
+    return str.split('').reverse().join('');
+  }
+};