diff --git a/src/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.cs b/src/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.cs
index b9e64ca855d1..7395de80b056 100644
--- a/src/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.cs
+++ b/src/System.Text.Json/src/System/Text/Json/Writer/JsonWriterHelper.cs
@@ -172,21 +172,38 @@ internal static void ValidateNumber(ReadOnlySpan<byte> utf8FormattedNumber)
                 return;
             }
 
+            // The non digit character inside the number
             byte val = utf8FormattedNumber[i];
 
             if (val == '.')
             {
                 i++;
+
+                while (i < utf8FormattedNumber.Length && JsonHelpers.IsDigit(utf8FormattedNumber[i]))
+                {
+                    i++;
+                }
+
+                if (utf8FormattedNumber.Length < i)
+                {
+                    throw new ArgumentException(SR.RequiredDigitNotFoundEndOfData, nameof(utf8FormattedNumber));
+                }
             }
-            else if (val == 'e' || val == 'E')
+
+            if (i == utf8FormattedNumber.Length)
+            {
+                return;
+            }
+
+            val = utf8FormattedNumber[i];
+
+            if (val == 'e' || val == 'E')
             {
                 i++;
 
-                if (i >= utf8FormattedNumber.Length)
+                if (utf8FormattedNumber.Length <= i)
                 {
-                    throw new ArgumentException(
-                        SR.RequiredDigitNotFoundEndOfData,
-                        nameof(utf8FormattedNumber));
+                    throw new ArgumentException(SR.RequiredDigitNotFoundEndOfData, nameof(utf8FormattedNumber));
                 }
 
                 val = utf8FormattedNumber[i];
@@ -203,11 +220,9 @@ internal static void ValidateNumber(ReadOnlySpan<byte> utf8FormattedNumber)
                     nameof(utf8FormattedNumber));
             }
 
-            if (i >= utf8FormattedNumber.Length)
+            if (utf8FormattedNumber.Length <= i)
             {
-                throw new ArgumentException(
-                    SR.RequiredDigitNotFoundEndOfData,
-                    nameof(utf8FormattedNumber));
+                throw new ArgumentException(SR.RequiredDigitNotFoundEndOfData, nameof(utf8FormattedNumber));
             }
 
             while (i < utf8FormattedNumber.Length && JsonHelpers.IsDigit(utf8FormattedNumber[i]))
diff --git a/src/System.Text.Json/tests/JsonElementWriteTests.cs b/src/System.Text.Json/tests/JsonElementWriteTests.cs
index 7866ef6cf17a..25830ea6274d 100644
--- a/src/System.Text.Json/tests/JsonElementWriteTests.cs
+++ b/src/System.Text.Json/tests/JsonElementWriteTests.cs
@@ -30,11 +30,39 @@ public static void WriteNumber(bool indented)
         }
 
         [Theory]
-        [InlineData(false)]
-        [InlineData(true)]
-        public static void WriteNumberScientific(bool indented)
+        [InlineData("1e6", false)]
+        [InlineData("1e6", true)]
+        [InlineData("1e+6", false)]
+        [InlineData("1e+6", true)]
+        [InlineData("1e-6", false)]
+        [InlineData("1e-6", true)]
+        [InlineData("-1e6", false)]
+        [InlineData("-1e6", true)]
+        [InlineData("-1e+6", true)]
+        [InlineData("-1e+6", true)]
+        [InlineData("-1e-6", false)]
+        [InlineData("-1e-6", true)]
+        public static void WriteNumberScientific(string value, bool indented)
+        {
+            WriteSimpleValue(indented, value);
+        }
+
+        [Theory]
+        [InlineData("5.012e-20", false)]
+        [InlineData("5.012e-20", true)]
+        [InlineData("5.012e20", false)]
+        [InlineData("5.012e20", true)]
+        [InlineData("5.012e+20", false)]
+        [InlineData("5.012e+20", true)]
+        [InlineData("-5.012e-20", false)]
+        [InlineData("-5.012e-20", true)]
+        [InlineData("-5.012e20", false)]
+        [InlineData("-5.012e20", true)]
+        [InlineData("-5.012e+20", false)]
+        [InlineData("-5.012e+20", true)]
+        public static void WriteNumberDecimalScientific(string value, bool indented)
         {
-            WriteSimpleValue(indented, "1e6");
+            WriteSimpleValue(indented, value);
         }
 
         [Theory]
diff --git a/src/System.Text.Json/tests/Utf8JsonWriterTests.cs b/src/System.Text.Json/tests/Utf8JsonWriterTests.cs
index 8b8500894ecd..1cc9e0e12bbb 100644
--- a/src/System.Text.Json/tests/Utf8JsonWriterTests.cs
+++ b/src/System.Text.Json/tests/Utf8JsonWriterTests.cs
@@ -3747,6 +3747,7 @@ public void WriteNumbers(bool formatted, bool skipValidation, string keyString)
             doubles[2] = double.MinValue;
             doubles[3] = 12.345e1;
             doubles[4] = -123.45e1;
+
             for (int i = 5; i < numberOfItems; i++)
             {
                 var value = random.NextDouble();