diff --git a/DIRECTORY.md b/DIRECTORY.md
index dccfbb7c9a..8cd38b0042 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -198,6 +198,7 @@
 * [ShorsAlgorithm](Maths/ShorsAlgorithm.js)
 * [SieveOfEratosthenes](Maths/SieveOfEratosthenes.js)
 * [SimpsonIntegration](Maths/SimpsonIntegration.js)
+ * [SimpleInterest](Maths/SimpleIntrest.js)
 * [Softmax](Maths/Softmax.js)
 * [SquareRoot](Maths/SquareRoot.js)
 * [SumOfDigits](Maths/SumOfDigits.js)
diff --git a/Maths/SimpleInterest.js b/Maths/SimpleInterest.js
new file mode 100644
index 0000000000..fbc7622785
--- /dev/null
+++ b/Maths/SimpleInterest.js
@@ -0,0 +1,15 @@
+/**
+ * @function SimpleInterest
+ * @description to calculate the amount of interest charged on a sum at a given rate and for a given period of time
+ * @param {number} principal - input: the principal amount
+ * @param {number} interestRate - input: the rate of interest in percentage
+ * @param {number} time - input: the time period in year
+ * @return {number} simpleInterest
+ */
+
+const SimpleInterest = (principal, interestRate, time) => {
+ const simpleInterest = Math.floor((principal * interestRate * time) / 100)
+ return simpleInterest
+}
+
+export { SimpleInterest }
diff --git a/Maths/test/SimpleInterest.test.js b/Maths/test/SimpleInterest.test.js
new file mode 100644
index 0000000000..054b740746
--- /dev/null
+++ b/Maths/test/SimpleInterest.test.js
@@ -0,0 +1,13 @@
+import { SimpleInterest } from '../SimpleInterest'
+
+describe('Testing Simple Interest Rate calculate function', () => {
+ it('should 750 for principal = 5000, rate = 5%, time = 3 yrs', () => {
+ expect(SimpleInterest(5000, 5, 3)).toBe(750)
+ })
+ it('should 750 for principal = 1000, rate = 3%, time = 2 yrs', () => {
+ expect(SimpleInterest(10000, 3, 2)).toBe(600)
+ })
+ it('should 750 for principal = 40000, rate = 0.1%, time = 10 yrs', () => {
+ expect(SimpleInterest(40000, 0.1, 10)).toBe(400)
+ })
+})
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://patch-diff.githubusercontent.com/raw/TheAlgorithms/JavaScript/pull/1081.diff">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://patch-diff.githubusercontent.com/raw/TheAlgorithms/JavaScript/pull/1081.diff" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>