diff --git a/src/PhpSpreadsheet/Cell/AddressHelper.php b/src/PhpSpreadsheet/Cell/AddressHelper.php
index cde31a13..0dabc6e0 100644
--- a/src/PhpSpreadsheet/Cell/AddressHelper.php
+++ b/src/PhpSpreadsheet/Cell/AddressHelper.php
@@ -72,7 +72,7 @@ class AddressHelper
             foreach ($temp as &$value) {
                 //    Only replace in alternate array entries (i.e. non-quoted blocks)
                 if ($key = !$key) {
-                    preg_match_all('/(R(\[?-?\d*\]?))(C(\[?-?\d*\]?))/', $value, $cellReferences, PREG_SET_ORDER + PREG_OFFSET_CAPTURE);
+                    preg_match_all('/(?:R(?:(?:\[-?\d*\])|(?:\d*))?)(?:C(?:(?:\[-?\d*\])|(?:\d*))?)/i', $value, $cellReferences, PREG_SET_ORDER + PREG_OFFSET_CAPTURE);
                     //    Reverse the matches array, otherwise all our offsets will become incorrect if we modify our way
                     //        through the formula from left to right. Reversing means that we work right to left.through
                     //        the formula
diff --git a/tests/PhpSpreadsheetTests/Cell/AddressHelperTest.php b/tests/PhpSpreadsheetTests/Cell/AddressHelperTest.php
index 26e0a14b..58c696ef 100644
--- a/tests/PhpSpreadsheetTests/Cell/AddressHelperTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/AddressHelperTest.php
@@ -143,7 +143,7 @@ class AddressHelperTest extends TestCase
     /**
      * @dataProvider providerConvertFormulaToA1FromR1C1Relative
      */
-    public function testConvertFormulaToA1R1C1Relative(string $expectedValue, string $formula, int $row, int $column): void
+    public function testConvertFormulaToA1FromR1C1Relative(string $expectedValue, string $formula, int $row, int $column): void
     {
         $actualValue = AddressHelper::convertFormulaToA1($formula, $row, $column);
 
diff --git a/tests/data/Cell/ConvertFormulaToA1FromR1C1Absolute.php b/tests/data/Cell/ConvertFormulaToA1FromR1C1Absolute.php
index cc67d308..f1b16728 100644
--- a/tests/data/Cell/ConvertFormulaToA1FromR1C1Absolute.php
+++ b/tests/data/Cell/ConvertFormulaToA1FromR1C1Absolute.php
@@ -1,8 +1,16 @@
 <?php
 
 return [
-    ['=B4+C4', '=R4C2+R4C3'],
-    ['=B3+C3', '=R[2]C[1]+R[2]C[2]'],
-    ['=SUM(B1:B4)', '=SUM(R1C2:R4C2)'],
-    ['=CONCAT("Result of formula expression =R1C1+R1C2 is: ", A1+B1)', '=CONCAT("Result of formula expression =R1C1+R1C2 is: ", R1C1+R1C2)'],
+    // Basic arithmetic
+    ['=D3+F7+G4+C6+5', '=R3C4+R7C6+R4C7+R6C3+5'],
+    ['=D3-F7-G4-C6-5', '=R3C4-R7C6-R4C7-R6C3-5'],
+    ['=D3*F7*G4*C6*5', '=R3C4*R7C6*R4C7*R6C3*5'],
+    ['=D3/F7/G4/C6/5', '=R3C4/R7C6/R4C7/R6C3/5'],
+    // Formulas
+    ['=SUM(E1:E5)', '=SUM(R1C5:R5C5)'],
+    ['=SUM(E1:E5, D5)', '=SUM(R1C5:R5C5, R5C4)'],
+    ['=SUM(E1:E5, D5)-C5', '=SUM(R1C5:R5C5, R5C4)-R5C3'],
+    ['=IF(E1>E2, E3, E4)', '=IF(R1C5>R2C5, R3C5, R4C5)'],
+    // String literals
+    ['=CONCAT("Result of formula expression =R3C3+R4C3 is: ", C3+C4)', '=CONCAT("Result of formula expression =R3C3+R4C3 is: ", R3C3+R4C3)'],
 ];
diff --git a/tests/data/Cell/ConvertFormulaToA1FromR1C1Relative.php b/tests/data/Cell/ConvertFormulaToA1FromR1C1Relative.php
index 4686cc5a..2effc81e 100644
--- a/tests/data/Cell/ConvertFormulaToA1FromR1C1Relative.php
+++ b/tests/data/Cell/ConvertFormulaToA1FromR1C1Relative.php
@@ -1,7 +1,21 @@
 <?php
 
 return [
-    ['=N18+O18', '=R[2]C[1]+R[2]C[2]', 16, 13],
+    // Basic arithmetic without the current row/column
+    ['=D3+F7+G4+C6+5', '=R[-2]C[-1]+R[2]C[1]+R[-1]C[2]+R[1]C[-2]+5', 5, 5],
+    ['=D3-F7-G4-C6-5', '=R[-2]C[-1]-R[2]C[1]-R[-1]C[2]-R[1]C[-2]-5', 5, 5],
+    ['=D3*F7*G4*C6*5', '=R[-2]C[-1]*R[2]C[1]*R[-1]C[2]*R[1]C[-2]*5', 5, 5],
+    ['=D3/F7/G4/C6/5', '=R[-2]C[-1]/R[2]C[1]/R[-1]C[2]/R[1]C[-2]/5', 5, 5],
+    // Basic Arithmetic with the current row/column
+    ['=E3+E7+G5+C5+E5+5', '=R[-2]C+R[2]C+RC[2]+RC[-2]+RC+5', 5, 5],
+    ['=E3-E7-G5-C5-E5-5', '=R[-2]C-R[2]C-RC[2]-RC[-2]-RC-5', 5, 5],
+    ['=E3*E7*G5*C5*E5*5', '=R[-2]C*R[2]C*RC[2]*RC[-2]*RC*5', 5, 5],
+    ['=E3/E7/G5/C5/E5/5', '=R[-2]C/R[2]C/RC[2]/RC[-2]/RC/5', 5, 5],
+    // Formulas
     ['=SUM(E1:E5)', '=SUM(R[-4]C:RC)', 5, 5],
+    ['=SUM(E1:E5, D5)', '=SUM(R[-4]C:RC, RC[-1])', 5, 5],
+    ['=SUM(E1:E5, D5)-C5', '=SUM(R[-4]C:RC, RC[-1])-RC[-2]', 5, 5],
+    ['=IF(E1>E2, E3, E4)', '=IF(R[-4]C>R[-3]C, R[-2]C, R[-1]C)', 5, 5],
+    // String literals
     ['=CONCAT("Result of formula expression =R[-2]C[-2]+R[-1]C[-2] is: ", C3+C4)', '=CONCAT("Result of formula expression =R[-2]C[-2]+R[-1]C[-2] is: ", R[-2]C[-2]+R[-1]C[-2])', 5, 5],
 ];
diff --git a/tests/data/Cell/ConvertFormulaToA1FromSpreadsheetXml.php b/tests/data/Cell/ConvertFormulaToA1FromSpreadsheetXml.php
index 590d4d0d..3cfd8ee9 100644
--- a/tests/data/Cell/ConvertFormulaToA1FromSpreadsheetXml.php
+++ b/tests/data/Cell/ConvertFormulaToA1FromSpreadsheetXml.php
@@ -1,7 +1,16 @@
 <?php
 
 return [
-    ['=B4+C4', 'of:=[.B4]+[.C4]'],
-    ['=SUM(B1:B4)', 'of:=SUM([.B1:.B4])'],
-    ['=CONCAT("Result of formula expression =[.B4]+[.C4] is: ", B4+C4)', 'of:=CONCAT("Result of formula expression =[.B4]+[.C4] is: ", [.B4]+[.C4])'],
+    // Basic arithmetic
+    ['=D3+F7+G4+C6+5', 'of:=[.D3]+[.F7]+[.G4]+[.C6]+5'],
+    ['=D3-F7-G4-C6-5', 'of:=[.D3]-[.F7]-[.G4]-[.C6]-5'],
+    ['=D3*F7*G4*C6*5', 'of:=[.D3]*[.F7]*[.G4]*[.C6]*5'],
+    ['=D3/F7/G4/C6/5', 'of:=[.D3]/[.F7]/[.G4]/[.C6]/5'],
+    // Formulas
+    ['=SUM(E1:E5)', 'of:=SUM([.E1:.E5])'],
+    ['=SUM(E1:E5, D5)', 'of:=SUM([.E1:.E5], [.D5])'],
+    ['=SUM(E1:E5, D5)-C5', 'of:=SUM([.E1:.E5], [.D5])-[.C5]'],
+    ['=IF(E1>E2, E3, E4)', 'of:=IF([.E1]>[.E2], [.E3], [.E4])'],
+    // String literals
+    ['=CONCAT("Result of formula expression =[.C3]+[.C4] is: ", C3+C4)', 'of:=CONCAT("Result of formula expression =[.C3]+[.C4] is: ", [.C3]+[.C4])'],
 ];