diff --git a/src/arrays.js b/src/arrays.js
index 968a168b..e2238dde 100644
--- a/src/arrays.js
+++ b/src/arrays.js
@@ -14,12 +14,21 @@ const each = (elements, cb) => {
   // This only needs to work with arrays.
   // You should also pass the index into `cb` as the second argument
   // based off http://underscorejs.org/#each
+  for (let i = 0; i < elements.length; i++) {
+    cb(elements[i], i);
+  }
 };
 
+
 const map = (elements, cb) => {
   // Do NOT use .map, to complete this function.
   // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
   // Return the new array.
+  const mappedElements = [];
+  for (let i = 0; i < elements.length; i++) {
+    mappedElements.push(cb(elements[i]));
+  }
+  return mappedElements;
 };
 
 const reduce = (elements, cb, startingValue) => {
@@ -28,6 +37,16 @@ const reduce = (elements, cb, startingValue) => {
   // Elements will be passed one by one into `cb` along with the `startingValue`.
   // `startingValue` should be the first argument passed to `cb` and the array element should be the second argument.
   // `startingValue` is the starting value.  If `startingValue` is undefined then make `elements[0]` the initial value.
+  let memo = startingValue;
+  let i = 0;
+  if (startingValue === undefined) {
+    memo = elements[0];
+    i++;
+  }
+  for (let i = 0; i < elements.length; i++) {
+    memo = cb(memo, elements[i]);
+  }
+  return memo;
 };
 
 const find = (elements, cb) => {
@@ -35,12 +54,20 @@ const find = (elements, cb) => {
   // Look through each value in `elements` and pass each element to `cb`.
   // If `cb` returns `true` then return that element.
   // Return `undefined` if no elements pass the truth test.
+  for (let i = 0; i < elements.length; i++) {
+    if(cb(elements[i])) return elements[i];
+  }
 };
 
 const filter = (elements, cb) => {
   // Do NOT use .filter, to complete this function.
   // Similar to `find` but you will return an array of all elements that passed the truth test
   // Return an empty array if no elements pass the truth test
+  const filteredItems = [];
+  elements.forEach((item) => {
+    if (cb(item)) filteredItems.push(item);
+  });
+  return filteredItems;
 };
 
 /* STRETCH PROBLEM */
@@ -48,6 +75,18 @@ const filter = (elements, cb) => {
 const flatten = (elements) => {
   // Flattens a nested array (the nesting can be to any depth).
   // Example: flatten([1, [2], [3, [[4]]]]); => [1, 2, 3, 4];
+  const res = [];
+  const func = (arr) => {
+    for (let i = 0; i < arr.length; i++) {
+      if (Array.isArray(arr[i])) {
+        func(arr[i]);
+    } else {
+      res.push(arr[i]);
+    }
+  }
+ }
+ func(elements);
+ return res;
 };
 
 /* eslint-enable no-unused-vars, max-len */
diff --git a/src/callbacks.js b/src/callbacks.js
index 53917475..c229258e 100644
--- a/src/callbacks.js
+++ b/src/callbacks.js
@@ -1,26 +1,46 @@
 const firstItem = (arr, cb) => {
   // firstItem passes the first item of the given array to the callback function.
+  const item = arr[0];
+  cb(item);
 };
 
 const getLength = (arr, cb) => {
   // getLength passes the length of the array into the callback.
+  const length = arr.length;
+  cb(length);
 };
 
 const last = (arr, cb) => {
   // last passes the last item of the array into the callback.
+  const lastItem = arr [arr.length - 1];
+  cb(lastItem);
 };
 
 const sumNums = (x, y, cb) => {
   // sumNums adds two numbers (x, y) and passes the result to the callback.
+  const sum = x + y;
+  cb(sum);
 };
 
 const multiplyNums = (x, y, cb) => {
   // multiplyNums multiplies two numbers and passes the result to the callback.
+  const prod = x * y;
+  cb(prod);
 };
 
 const contains = (item, list, cb) => {
   // contains checks if an item is present inside of the given array/list.
   // Pass true to the callback if it is, otherwise pass false.
+  test = false;
+  
+  for (let i = 0; i <= arr.length; i++) {
+    if (item === arr[i]) {
+      test = true;
+      // return test;
+      // break;
+    }
+  }
+  cb(test);
 };
 
 /* STRETCH PROBLEM */
@@ -29,6 +49,19 @@ const removeDuplicates = (array, cb) => {
   // removeDuplicates removes all duplicate values from the given array.
   // Pass the duplicate free array to the callback function.
   // Do not mutate the original array.
+  const res = [];
+  for (let i = 0; i <= newArr.length; i++) {
+    if(res.indexOf(array[i] !== -1) res.push(array[i]);
+    // for (let a = 1; a < newArr.length; a++) {
+    //   if (newArr[i] === newarr[a]) {
+    //     newArr.splice(a, 1);
+    //     console.log(newArr);
+    //     a = i+1;
+
+    //   }
+    // }
+  }
+  cb(res);
 };
 
 /* eslint-enable */
diff --git a/src/closure.js b/src/closure.js
index 2a3cee37..6dbaa8ee 100644
--- a/src/closure.js
+++ b/src/closure.js
@@ -5,17 +5,30 @@ const counter = () => {
   // Example: const newCounter = counter();
   // newCounter(); // 1
   // newCounter(); // 2
+  let count = 0;
+  return () => ++count;
 };
 
 const counterFactory = () => {
   // Return an object that has two methods called `increment` and `decrement`.
   // `increment` should increment a counter variable in closure scope and return it.
   // `decrement` should decrement the counter variable and return it.
+  let count = 0;
+  return {
+    increment: () => ++count,
+    decrement: () => --count,
+  };
 };
 
 const limitFunctionCallCount = (cb, n) => {
   // Should return a function that invokes `cb`.
   // The returned function should only allow `cb` to be invoked `n` times.
+  let callCount = 0;
+  return (...args) => {
+    if (callCount === n) return null;
+    callCount++;
+    return cb();
+  };
 };
 
 /* STRETCH PROBLEM */
diff --git a/src/objects.js b/src/objects.js
index 2898d4d4..3cc25507 100644
--- a/src/objects.js
+++ b/src/objects.js
@@ -5,22 +5,30 @@ const keys = (obj) => {
   // Retrieve all the names of the object's properties.
   // Return the keys as strings in an array.
   // Based on http://underscorejs.org/#keys
+  return Object.keys(obj);
 };
 
 const values = (obj) => {
   // Return all of the values of the object's own properties.
   // Ignore functions
   // http://underscorejs.org/#values
+  return Object.keys(obj).map(key => obj[key]);
 };
 
 const mapObject = (obj, cb) => {
   // Like map for arrays, but for objects. Transform the value of each property in turn.
   // http://underscorejs.org/#mapObject
+  const mappedObject = {};
+  Object.keys(obj).forEach((key) => {
+    obj[key] = cb(obj[key]);
+  });
+  return mappedObject;
 };
 
 const pairs = (obj) => {
   // Convert an object into a list of [key, value] pairs.
   // http://underscorejs.org/#pairs
+  return Object.keys(obj).map(key => [key, obj[key]]);
 };
 
 /* STRETCH PROBLEMS */
@@ -29,12 +37,24 @@ const invert = (obj) => {
   // Returns a copy of the object where the keys have become the values and the values the keys.
   // Assume that all of the object's values will be unique and string serializable.
   // http://underscorejs.org/#invert
+  const invertedObject = {};
+  Object.keys(obj).forEach((key) => {
+    const value = obj[key];
+    obj[value] = key;
+    delete obj[key];
+  });
+  return invertedObject;
 };
 
 const defaults = (obj, defaultProps) => {
   // Fill in undefined properties that match properties on the `defaultProps` parameter object.
   // Return `obj`.
   // http://underscorejs.org/#defaults
+  Object.keys(defaultProps).forEach((key) => {
+    if (Object.prototype.hasOwnProperty.call(obj, key)) return;
+    obj[key] = defaultProps[key];
+  });
+  return obj;
 };
 
 /* eslint-enable no-unused-vars */
diff --git a/yarn.lock b/yarn.lock
index 8a8700bb..2ee9657c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1,7 +1,5 @@
 # THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
 # yarn lockfile v1
-
-
 abab@^1.0.3:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/abab/-/abab-1.0.4.tgz#5faad9c2c07f60dd76770f71cf025b62a63cfd4e"
@@ -151,7 +149,7 @@ asn1@~0.2.3:
   version "0.2.3"
   resolved "https://registry.yarnpkg.com/asn1/-/asn1-0.2.3.tgz#dac8787713c9966849fc8180777ebe9c1ddf3b86"
 
-assert-plus@1.0.0, assert-plus@^1.0.0:
+assert-plus@^1.0.0, assert-plus@1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/assert-plus/-/assert-plus-1.0.0.tgz#f12e0f3c5d77b0b1cdd9146942e4e96c1e4dd525"
 
@@ -753,18 +751,18 @@ browserslist@^2.1.2:
     caniuse-lite "^1.0.30000792"
     electron-to-chromium "^1.3.30"
 
-bser@1.0.2:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/bser/-/bser-1.0.2.tgz#381116970b2a6deea5646dd15dd7278444b56169"
-  dependencies:
-    node-int64 "^0.4.0"
-
 bser@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/bser/-/bser-2.0.0.tgz#9ac78d3ed5d915804fd87acb158bc797147a1719"
   dependencies:
     node-int64 "^0.4.0"
 
+bser@1.0.2:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/bser/-/bser-1.0.2.tgz#381116970b2a6deea5646dd15dd7278444b56169"
+  dependencies:
+    node-int64 "^0.4.0"
+
 builtin-modules@^1.0.0, builtin-modules@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/builtin-modules/-/builtin-modules-1.1.1.tgz#270f076c5a72c02f5b65a47df94c5fe3a278892f"
@@ -898,7 +896,7 @@ color-name@^1.1.1:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/color-name/-/color-name-1.1.3.tgz#a7d0558bd89c42f795dd42328f740831ca53bc25"
 
-combined-stream@1.0.6, combined-stream@~1.0.5:
+combined-stream@~1.0.5, combined-stream@1.0.6:
   version "1.0.6"
   resolved "https://registry.yarnpkg.com/combined-stream/-/combined-stream-1.0.6.tgz#723e7df6e801ac5613113a7e445a9b69cb632818"
   dependencies:
@@ -944,7 +942,7 @@ core-js@^2.4.0, core-js@^2.5.0:
   version "2.5.3"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.5.3.tgz#8acc38345824f16d8365b7c9b4259168e8ed603e"
 
-core-util-is@1.0.2, core-util-is@~1.0.0:
+core-util-is@~1.0.0, core-util-is@1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"
 
@@ -954,7 +952,7 @@ cryptiles@3.x.x:
   dependencies:
     boom "5.x.x"
 
-cssom@0.3.x, "cssom@>= 0.3.2 < 0.4.0":
+"cssom@>= 0.3.2 < 0.4.0", cssom@0.3.x:
   version "0.3.2"
   resolved "https://registry.yarnpkg.com/cssom/-/cssom-0.3.2.tgz#b8036170c79f07a90ff2f16e22284027a243848b"
 
@@ -1051,6 +1049,12 @@ diff@^3.0.0:
   version "3.5.0"
   resolved "https://registry.yarnpkg.com/diff/-/diff-3.5.0.tgz#800c0dd1e0a8bfbc95835c202ad220fe317e5a12"
 
+doctrine@^2.0.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/doctrine/-/doctrine-2.1.0.tgz#5cd01fc101621b42c4cd7f5d1a66243716d3f39d"
+  dependencies:
+    esutils "^2.0.2"
+
 doctrine@1.5.0:
   version "1.5.0"
   resolved "https://registry.yarnpkg.com/doctrine/-/doctrine-1.5.0.tgz#379dce730f6166f76cefa4e6707a159b02c5a6fa"
@@ -1058,12 +1062,6 @@ doctrine@1.5.0:
     esutils "^2.0.2"
     isarray "^1.0.0"
 
-doctrine@^2.0.0:
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/doctrine/-/doctrine-2.1.0.tgz#5cd01fc101621b42c4cd7f5d1a66243716d3f39d"
-  dependencies:
-    esutils "^2.0.2"
-
 ecc-jsbn@~0.1.1:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/ecc-jsbn/-/ecc-jsbn-0.1.1.tgz#0fc73a9ed5f0d53c38193398523ef7e543777505"
@@ -1122,7 +1120,7 @@ es6-set@~0.1.5:
     es6-symbol "3.1.1"
     event-emitter "~0.3.5"
 
-es6-symbol@3.1.1, es6-symbol@^3.1.1, es6-symbol@~3.1.1:
+es6-symbol@^3.1.1, es6-symbol@~3.1.1, es6-symbol@3.1.1:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/es6-symbol/-/es6-symbol-3.1.1.tgz#bf00ef4fdab6ba1b46ecb7b629b4c7ed5715cc77"
   dependencies:
@@ -1359,14 +1357,14 @@ extglob@^2.0.4:
     snapdragon "^0.8.1"
     to-regex "^3.0.1"
 
-extsprintf@1.3.0:
-  version "1.3.0"
-  resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.3.0.tgz#96918440e3041a7a414f8c52e3c574eb3c3e1e05"
-
 extsprintf@^1.2.0:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.4.0.tgz#e2689f8f356fad62cca65a3a91c5df5f9551692f"
 
+extsprintf@1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/extsprintf/-/extsprintf-1.3.0.tgz#96918440e3041a7a414f8c52e3c574eb3c3e1e05"
+
 fast-deep-equal@^1.0.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-1.1.0.tgz#c053477817c86b51daa853c81e059b733d023614"
@@ -1685,7 +1683,7 @@ inflight@^1.0.4:
     once "^1.3.0"
     wrappy "1"
 
-inherits@2, inherits@^2.0.3, inherits@~2.0.3:
+inherits@^2.0.3, inherits@~2.0.3, inherits@2:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
 
@@ -1913,7 +1911,7 @@ is-windows@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/is-windows/-/is-windows-1.0.2.tgz#d1850eb9791ecd18e6182ce12a30f396634bb19d"
 
-isarray@1.0.0, isarray@^1.0.0, isarray@~1.0.0:
+isarray@^1.0.0, isarray@~1.0.0, isarray@1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/isarray/-/isarray-1.0.0.tgz#bb935d48582cba168c06834957a54a3e07124f11"
 
@@ -2440,10 +2438,6 @@ minimatch@^3.0.2, minimatch@^3.0.3, minimatch@^3.0.4:
   dependencies:
     brace-expansion "^1.1.7"
 
-minimist@0.0.8:
-  version "0.0.8"
-  resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.8.tgz#857fcabfc3397d2625b8228262e86aa7a011b05d"
-
 minimist@^1.1.1:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-1.2.0.tgz#a35008b20f41383eec1fb914f4cd5df79a264284"
@@ -2452,6 +2446,10 @@ minimist@~0.0.1:
   version "0.0.10"
   resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.10.tgz#de3f98543dbf96082be48ad1a0c7cda836301dcf"
 
+minimist@0.0.8:
+  version "0.0.8"
+  resolved "https://registry.yarnpkg.com/minimist/-/minimist-0.0.8.tgz#857fcabfc3397d2625b8228262e86aa7a011b05d"
+
 mixin-deep@^1.2.0:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/mixin-deep/-/mixin-deep-1.3.1.tgz#a49e7268dce1a0d9698e45326c5626df3543d0fe"
@@ -2934,16 +2932,16 @@ resolve-url@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/resolve-url/-/resolve-url-0.2.1.tgz#2c637fe77c893afd2a663fe21aa9080068e2052a"
 
-resolve@1.1.7:
-  version "1.1.7"
-  resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.1.7.tgz#203114d82ad2c5ed9e8e0411b3932875e889e97b"
-
 resolve@^1.1.6, resolve@^1.2.0, resolve@^1.5.0:
   version "1.5.0"
   resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.5.0.tgz#1f09acce796c9a762579f31b2c1cc4c3cddf9f36"
   dependencies:
     path-parse "^1.0.5"
 
+resolve@1.1.7:
+  version "1.1.7"
+  resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.1.7.tgz#203114d82ad2c5ed9e8e0411b3932875e889e97b"
+
 restore-cursor@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/restore-cursor/-/restore-cursor-1.0.1.tgz#34661f46886327fed2991479152252df92daa541"
@@ -3003,7 +3001,7 @@ sax@^1.2.1:
   version "1.2.4"
   resolved "https://registry.yarnpkg.com/sax/-/sax-1.2.4.tgz#2816234e2378bddc4e5354fab5caa895df7100d9"
 
-"semver@2 || 3 || 4 || 5", semver@^5.3.0, semver@^5.4.1:
+semver@^5.3.0, semver@^5.4.1, "semver@2 || 3 || 4 || 5":
   version "5.5.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.5.0.tgz#dc4bbc7a6ca9d916dee5d43516f0092b58f7b8ab"
 
@@ -3169,6 +3167,12 @@ static-extend@^0.1.1:
     define-property "^0.2.5"
     object-copy "^0.1.0"
 
+string_decoder@~1.0.3:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/string_decoder/-/string_decoder-1.0.3.tgz#0fc67d7c141825de94282dd536bec6b9bce860ab"
+  dependencies:
+    safe-buffer "~5.1.0"
+
 string-length@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/string-length/-/string-length-1.0.1.tgz#56970fb1c38558e9e70b728bf3de269ac45adfac"
@@ -3190,12 +3194,6 @@ string-width@^2.0.0:
     is-fullwidth-code-point "^2.0.0"
     strip-ansi "^4.0.0"
 
-string_decoder@~1.0.3:
-  version "1.0.3"
-  resolved "https://registry.yarnpkg.com/string_decoder/-/string_decoder-1.0.3.tgz#0fc67d7c141825de94282dd536bec6b9bce860ab"
-  dependencies:
-    safe-buffer "~5.1.0"
-
 stringstream@~0.0.5:
   version "0.0.5"
   resolved "https://registry.yarnpkg.com/stringstream/-/stringstream-0.0.5.tgz#4e484cd4de5a0bbbee18e46307710a8a81621878"
@@ -3212,16 +3210,16 @@ strip-ansi@^4.0.0:
   dependencies:
     ansi-regex "^3.0.0"
 
-strip-bom@3.0.0, strip-bom@^3.0.0:
-  version "3.0.0"
-  resolved "https://registry.yarnpkg.com/strip-bom/-/strip-bom-3.0.0.tgz#2334c18e9c759f7bdd56fdef7e9ae3d588e68ed3"
-
 strip-bom@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/strip-bom/-/strip-bom-2.0.0.tgz#6219a85616520491f35788bdbf1447a99c7e6b0e"
   dependencies:
     is-utf8 "^0.2.0"
 
+strip-bom@^3.0.0, strip-bom@3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/strip-bom/-/strip-bom-3.0.0.tgz#2334c18e9c759f7bdd56fdef7e9ae3d588e68ed3"
+
 strip-json-comments@~2.0.1:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/strip-json-comments/-/strip-json-comments-2.0.1.tgz#3c531942e908c2697c0ec344858c286c7ca0a60a"
@@ -3450,10 +3448,6 @@ window-size@0.1.0:
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/window-size/-/window-size-0.1.0.tgz#5438cd2ea93b202efa3a19fe8887aee7c94f9c9d"
 
-wordwrap@0.0.2:
-  version "0.0.2"
-  resolved "https://registry.yarnpkg.com/wordwrap/-/wordwrap-0.0.2.tgz#b79669bb42ecb409f83d583cad52ca17eaa1643f"
-
 wordwrap@~0.0.2:
   version "0.0.3"
   resolved "https://registry.yarnpkg.com/wordwrap/-/wordwrap-0.0.3.tgz#a3d5da6cd5c0bc0008d37234bbaf1bed63059107"
@@ -3462,6 +3456,10 @@ wordwrap@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/wordwrap/-/wordwrap-1.0.0.tgz#27584810891456a4171c8d0226441ade90cbcaeb"
 
+wordwrap@0.0.2:
+  version "0.0.2"
+  resolved "https://registry.yarnpkg.com/wordwrap/-/wordwrap-0.0.2.tgz#b79669bb42ecb409f83d583cad52ca17eaa1643f"
+
 worker-farm@^1.3.1:
   version "1.6.0"
   resolved "https://registry.yarnpkg.com/worker-farm/-/worker-farm-1.6.0.tgz#aecc405976fab5a95526180846f0dba288f3a4a0"
@@ -3529,3 +3527,4 @@ yargs@~3.10.0:
     cliui "^2.1.0"
     decamelize "^1.0.0"
     window-size "0.1.0"
+