diff --git a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README.md b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README.md
index 33e0c86af993c..2df2ecc8331e0 100644
--- a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README.md	
+++ b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README.md	
@@ -115,15 +115,14 @@ class Solution {
  * @return {number}
  */
  var numberOfRounds = function(startTime, finishTime) {
-    let p1 = Math.ceil(toMinutes(startTime) / 15);
-    let p2 = Math.floor(toMinutes(finishTime) / 15);
+    let m1 = toMinutes(startTime), m2 = toMinutes(finishTime);
 
-    if (p1 > p2) {
-        p2 += 24 * 60 / 15;
+    if (m1 > m2) {
+        m2 += 24 * 60;
     }
 
-    let ans = p2 - p1;
-    return ans;
+    let ans = Math.floor(m2 / 15) - Math.ceil(m1 / 15);
+    return ans < 0 ? 0 : ans;
 };
 
 function toMinutes(time) {
diff --git a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README_EN.md b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README_EN.md
index 5d6a55d4cece9..0227064b1758f 100644
--- a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README_EN.md	
+++ b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/README_EN.md	
@@ -103,15 +103,14 @@ class Solution {
  * @return {number}
  */
  var numberOfRounds = function(startTime, finishTime) {
-    let p1 = Math.ceil(toMinutes(startTime) / 15);
-    let p2 = Math.floor(toMinutes(finishTime) / 15);
+    let m1 = toMinutes(startTime), m2 = toMinutes(finishTime);
 
-    if (p1 > p2) {
-        p2 += 24 * 60 / 15;
+    if (m1 > m2) {
+        m2 += 24 * 60;
     }
 
-    let ans = p2 - p1;
-    return ans;
+    let ans = Math.floor(m2 / 15) - Math.ceil(m1 / 15);
+    return ans < 0 ? 0 : ans;
 };
 
 function toMinutes(time) {
diff --git a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/Solution.js b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/Solution.js
index b0bb5a7ca3c9b..14edde37e6581 100644
--- a/solution/1900-1999/1904.The Number of Full Rounds You Have Played/Solution.js	
+++ b/solution/1900-1999/1904.The Number of Full Rounds You Have Played/Solution.js	
@@ -4,15 +4,14 @@
  * @return {number}
  */
  var numberOfRounds = function(startTime, finishTime) {
-    let p1 = Math.ceil(toMinutes(startTime) / 15);
-    let p2 = Math.floor(toMinutes(finishTime) / 15);
+    let m1 = toMinutes(startTime), m2 = toMinutes(finishTime);
 
-    if (p1 > p2) {
-        p2 += 24 * 60 / 15;
+    if (m1 > m2) {
+        m2 += 24 * 60;
     }
 
-    let ans = p2 - p1;
-    return ans;
+    let ans = Math.floor(m2 / 15) - Math.ceil(m1 / 15);
+    return ans < 0 ? 0 : ans;
 };
 
 function toMinutes(time) {