diff --git a/src/algorithms/math/is_prime.js b/src/algorithms/math/is_prime.js
index 0f291bac..a51523c3 100644
--- a/src/algorithms/math/is_prime.js
+++ b/src/algorithms/math/is_prime.js
@@ -7,8 +7,8 @@
  */
 const isprime = (num) => {
   const limit = Math.floor(Math.sqrt(num));
-  for (let i = 2; i <= limit; i++) {
-      if (num % i === 0) return false;
+  for (let i = 2; i <= limit; i += 1) {
+    if (num % i === 0) return false;
   }
   return num >= 2;
 };
diff --git a/src/algorithms/math/sum_all.js b/src/algorithms/math/sum_all.js
index 872775e0..8e45cff3 100644
--- a/src/algorithms/math/sum_all.js
+++ b/src/algorithms/math/sum_all.js
@@ -4,12 +4,12 @@
  * @return {Number}  sum sum of the range of numberse
  */
 const sumall = (arr) => {
-  var sum = 0;
-  var min = arr[0];
-  var max = arr[1];
-  var i =0;
-  for (i = min; i <= max; i = i + 1) {
-    sum = sum + i;
+  let sum = 0;
+  let min = arr[0];
+  let max = arr[1];
+  let i = 0;
+  for (i = min; i <= max; i+=1) {
+    sum+=i;
   }
   return sum;
 };
diff --git a/src/algorithms/search/naive_search.js b/src/algorithms/search/naive_search.js
index 8177a02f..b50cc416 100644
--- a/src/algorithms/search/naive_search.js
+++ b/src/algorithms/search/naive_search.js
@@ -7,8 +7,8 @@
 
 const naivesearch = (st, pattern) => {
   let count = 0;
-  for (let i = 0; i < st.length; i = i + 1) {
-    for (let j = 0; j < pattern.length; j = j + 1) {
+  for (let i = 0; i < st.length; i += 1) {
+    for (let j = 0; j < pattern.length; j += 1) {
       if (st[i + j] !== pattern[j]) break;
       if (j === pattern.length - 1) count += 1;
     }
diff --git a/test/algorithms/math/testSumAll.js b/test/algorithms/math/testSumAll.js
index 46c666cc..ad7658df 100644
--- a/test/algorithms/math/testSumAll.js
+++ b/test/algorithms/math/testSumAll.js
@@ -10,5 +10,4 @@ describe('sumALL', () => {
     assert.equal(sumall(3, 6), 18);
     assert.equal(sumall(37), true);
   });
-
 });