From 79f5cf99f68637b4e0db70eb1307e62e570300b8 Mon Sep 17 00:00:00 2001
From: MarkBaker <mark@lange.demon.co.uk>
Date: Tue, 17 May 2022 12:56:21 +0200
Subject: [PATCH] Resolve Issue #2833, NULL value handling in PRODUCT() Excel
 function

---
 .../Calculation/MathTrig/Operations.php              |  2 +-
 tests/data/Calculation/MathTrig/PRODUCT.php          | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php b/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
index 7fd302339..44e135262 100644
--- a/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
+++ b/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
@@ -108,7 +108,7 @@ class Operations
         // Loop through arguments
         foreach (Functions::flattenArray($args) as $arg) {
             // Is it a numeric value?
-            if (is_numeric($arg)) {
+            if (is_numeric($arg) || $arg === null) {
                 if ($returnValue === null) {
                     $returnValue = $arg;
                 } else {
diff --git a/tests/data/Calculation/MathTrig/PRODUCT.php b/tests/data/Calculation/MathTrig/PRODUCT.php
index 0e7c40802..ab5009535 100644
--- a/tests/data/Calculation/MathTrig/PRODUCT.php
+++ b/tests/data/Calculation/MathTrig/PRODUCT.php
@@ -48,6 +48,18 @@ return [
         -6.7800000000000002,
         -2,
     ],
+    [
+        0,
+        12.5,
+        null,
+        2.5,
+    ],
+    [
+        0,
+        12.5,
+        2.5,
+        null,
+    ],
     ['#VALUE!', 1, 'y', 3],
     [6, 1, '2', 3],
 ];