diff --git a/snippets/toDecimalMark.md b/snippets/toDecimalMark.md
new file mode 100644
index 000000000..79cea1840
--- /dev/null
+++ b/snippets/toDecimalMark.md
@@ -0,0 +1,17 @@
+### toDecimalMark
+
+Convert a float-point arithmetic to the [Decimal mark](https://en.wikipedia.org/wiki/Decimal_mark) form.
+
+Use `toString()` to convert the float `num` to a string, then use regex to separate every three characters of the integer part with a comma.
+
+ ```js
+const toDecimalMark = (num) => {
+  let cleanNum = num.toString().split('').filter(n => '0123456789.'.includes(n)).join('') 
+  let wholeNum = cleanNum.split('.')[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",")
+  let decNum = `.${cleanNum.split('.')[1]}`
+  return wholeNum + decNum;
+}
+// toDecimalMark(12305030388.9087) //-> '12,305,030,388.9087'
+// toDecimalMark(123.889087e2) //-> '12,388.9087'
+// toDecimalMark('12305abc030388.9087') // -> '12,305,030,388.9087'
+```
diff --git a/tag_database b/tag_database
index bc9f671f3..8b6dd43af 100644
--- a/tag_database
+++ b/tag_database
@@ -123,3 +123,4 @@ without:array
 words:string
 zip:array
 zipObject:array
+numberWithCommas:utility