diff --git a/package.json b/package.json
index e8f6b15..d67cbde 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,7 @@
     "typescript"
   ],
   "author": "Vien Dinh",
-  "version": "2.0.13",
+  "version": "2.0.14",
   "license": "MIT",
   "main": "dist/index.js",
   "typings": "dist/index.d.ts",
diff --git a/src/supermemo.test.ts b/src/supermemo.test.ts
index 564cb69..4aad8f9 100644
--- a/src/supermemo.test.ts
+++ b/src/supermemo.test.ts
@@ -28,13 +28,21 @@ describe('supermemo', () => {
   it('Grade: 2', () => {
     item = supermemo(item, 2);
 
-    expect(item).toEqual({ interval: 1, repetition: 0, efactor: 2.1399999999999997 });
+    expect(item).toEqual({
+      interval: 1,
+      repetition: 0,
+      efactor: 2.1399999999999997,
+    });
   });
 
   it('Grade: 1', () => {
     item = supermemo(item, 1);
 
-    expect(item).toEqual({ interval: 1, repetition: 0, efactor: 1.5999999999999996 });
+    expect(item).toEqual({
+      interval: 1,
+      repetition: 0,
+      efactor: 1.5999999999999996,
+    });
   });
 
   it('Grade: 0', () => {
diff --git a/src/supermemo.ts b/src/supermemo.ts
index 7743c1d..1e88d23 100644
--- a/src/supermemo.ts
+++ b/src/supermemo.ts
@@ -6,7 +6,10 @@ export type SuperMemoItem = {
 
 export type SuperMemoGrade = 0 | 1 | 2 | 3 | 4 | 5;
 
-export function supermemo(item: SuperMemoItem, grade: SuperMemoGrade): SuperMemoItem {
+export function supermemo(
+  item: SuperMemoItem,
+  grade: SuperMemoGrade
+): SuperMemoItem {
   let nextInterval: number;
   let nextRepetition: number;
   let nextEfactor: number;
@@ -27,7 +30,8 @@ export function supermemo(item: SuperMemoItem, grade: SuperMemoGrade): SuperMemo
     nextRepetition = 0;
   }
 
-  nextEfactor = item.efactor + (0.1 - (5 - grade) * (0.08 + (5 - grade) * 0.02));
+  nextEfactor =
+    item.efactor + (0.1 - (5 - grade) * (0.08 + (5 - grade) * 0.02));
 
   if (nextEfactor < 1.3) nextEfactor = 1.3;