diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_math_perm.py b/graalpython/com.oracle.graal.python.test/src/tests/test_math_perm.py
new file mode 100644
index 0000000000..0edf8d928a
--- /dev/null
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_math_perm.py
@@ -0,0 +1,51 @@
+# Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+#
+# The Universal Permissive License (UPL), Version 1.0
+#
+# Subject to the condition set forth below, permission is hereby granted to any
+# person obtaining a copy of this software, associated documentation and/or
+# data (collectively the "Software"), free of charge and under any and all
+# copyright rights in the Software, and any and all patent rights owned or
+# freely licensable by each licensor hereunder covering either (i) the
+# unmodified Software as contributed to or provided by such licensor, or (ii)
+# the Larger Works (as defined below), to deal in both
+#
+# (a) the Software, and
+#
+# (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
+# one is included with the Software each a "Larger Work" to which the Software
+# is contributed by such licensors),
+#
+# without restriction, including without limitation the rights to copy, create
+# derivative works of, display, perform, and distribute the Software and make,
+# use, sell, offer for sale, import, export, have made, and have sold the
+# Software and the Larger Work(s), and to sublicense the foregoing rights on
+# either these or other terms.
+#
+# This license is subject to the following condition:
+#
+# The above copyright notice and either this complete permission notice or at a
+# minimum a reference to the UPL must be included in all copies or substantial
+# portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import math
+
+
+def test_perm_matches_product():
+    assert math.perm(10, 0) == 1
+    assert math.perm(10, 1) == 10
+    assert math.perm(10, 2) == 90
+    assert math.perm(10, 3) == 720
+    assert math.perm(10, 7) == 604800
+    assert math.perm(10, 10) == 3628800
+    assert math.perm(10, 11) == 0
+    assert math.perm(10**20, 3) == 999999999999999999970000000000000000000200000000000000000000
diff --git a/graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MathModuleBuiltins.java b/graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MathModuleBuiltins.java
index 029f6ac3cf..8fb09debf7 100644
--- a/graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MathModuleBuiltins.java
+++ b/graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/MathModuleBuiltins.java
@@ -533,19 +533,16 @@ private BigInteger calculatePerm(BigInteger n, BigInteger k) {
             if (k.equals(BigInteger.ZERO)) {
                 return BigInteger.ONE;
             }
+            return permProduct(n, k);
+        }
+
+        // P(n, k) = P(n, j) * P(n - j, k - j) keeps the operands balanced.
+        private static BigInteger permProduct(BigInteger n, BigInteger k) {
             if (k.equals(BigInteger.ONE)) {
                 return n;
             }
-
-            BigInteger result = n;
-            BigInteger factor = n;
-            BigInteger i = BigInteger.ONE;
-            while (i.compareTo(k) < 0) {
-                factor = factor.subtract(BigInteger.ONE);
-                result = result.multiply(factor);
-                i = i.add(BigInteger.ONE);
-            }
-            return result;
+            BigInteger j = k.shiftRight(1);
+            return permProduct(n, j).multiply(permProduct(n.subtract(j), k.subtract(j)));
         }
 
         @Specialization