From 15c1b2eb36b2513d71957bccba0b71c46da26918 Mon Sep 17 00:00:00 2001
From: Mayur Dhavan <118877752+mayur-dhavan@users.noreply.github.com>
Date: Mon, 26 Oct 2026 00:10:10 +0530
Subject: [PATCH 1/2] Keep intcomma floats out of scientific notation

Enhance number formatting to handle scientific notation.
---
 src/humanize/number.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/humanize/number.py b/src/humanize/number.py
index 52a5356a..a06a6bf6 100644
--- a/src/humanize/number.py
+++ b/src/humanize/number.py
@@ -5,6 +5,7 @@
 __lazy_modules__ = {"bisect"}
 
 import bisect
+from decimal import Decimal
 
 from .i18n import _gettext as _
 from .i18n import _gettext_noop as N_
@@ -198,6 +199,12 @@ def intcomma(value: NumberOrString, ndigits: int | None = None) -> str:
         result = f"{value:,.{ndigits}f}"
     else:
         result = f"{value:,}"
+        if isinstance(value, float) and ("e" in result or "E" in result):
+            # repr-style float formatting switches to scientific notation
+            # (>= 1e16, < 1e-4); expand it so digits are still grouped.
+            result = format(Decimal(repr(value)), ",f")
+            if value.is_integer():
+                result += ".0"
     if thousands_sep != "," or decimal_sep != ".":
         result = result.translate(str.maketrans(",.", thousands_sep + decimal_sep))
     return result

From 2e55e12e63f607dbb54fa135b3116963943dd96e Mon Sep 17 00:00:00 2001
From: Mayur Dhavan <118877752+mayur-dhavan@users.noreply.github.com>
Date: Mon, 26 Oct 2026 00:10:59 +0530
Subject: [PATCH 2/2] Add intcomma regression tests for scientific-notation
 floats

Added test cases for floats in scientific notation to ensure correct formatting.
---
 tests/test_number.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/test_number.py b/tests/test_number.py
index 5fb12fa6..a93d1b02 100644
--- a/tests/test_number.py
+++ b/tests/test_number.py
@@ -75,6 +75,14 @@ def test_ordinal(test_input: str, expected: str) -> None:
         ([-math.inf], "-Inf"),
         (["nan"], "NaN"),
         (["-inf"], "-Inf"),
+        # Floats whose repr uses scientific notation stay expanded (issue #431)
+        ([1e16], "10,000,000,000,000,000.0"),
+        ([1.5e20], "150,000,000,000,000,000,000.0"),
+        ([-1e16], "-10,000,000,000,000,000.0"),
+        ([1e16, 0], "10,000,000,000,000,000"),
+        ([0.00001], "0.00001"),
+        ([1.23e-5], "0.0000123"),
+        ([1234.5e15], "1,234,500,000,000,000,000.0"),
     ],
 )
 def test_intcomma(