diff --git a/PhpOffice/PhpSpreadsheet/Calculation/Calculation.php b/PhpOffice/PhpSpreadsheet/Calculation/Calculation.php
index e8e899f..b16caa1 100644
--- a/PhpOffice/PhpSpreadsheet/Calculation/Calculation.php
+++ b/PhpOffice/PhpSpreadsheet/Calculation/Calculation.php
@@ -3858,8 +3858,10 @@ class Calculation
                 }
             }
 
+            $tIndex = \is_float($token) ? (int) $token : $token;
+
             // if the token is a binary operator, pop the top two values off the stack, do the operation, and push the result back on the stack
-            if (isset(self::$binaryOperators[$token])) {
+            if (isset(self::$binaryOperators[$tIndex])) {
                 //    We must have two operands, error if we don't
                 if (($operand2Data = $stack->pop()) === null) {
                     return $this->raiseFormulaError('Internal error - Operand value missing from stack');
diff --git a/PhpOffice/PhpSpreadsheet/Shared/OLE.php b/PhpOffice/PhpSpreadsheet/Shared/OLE.php
index efa7522..7f6a1fb 100644
--- a/PhpOffice/PhpSpreadsheet/Shared/OLE.php
+++ b/PhpOffice/PhpSpreadsheet/Shared/OLE.php
@@ -521,12 +521,12 @@ class OLE
         $res = '';
 
         for ($i = 0; $i < 4; ++$i) {
-            $hex = $low_part % 0x100;
+            $hex = (int) (((int) $low_part) % 0x100);
             $res .= pack('c', $hex);
             $low_part /= 0x100;
         }
         for ($i = 0; $i < 4; ++$i) {
-            $hex = $high_part % 0x100;
+            $hex = (int) (((int) $high_part) % 0x100);
             $res .= pack('c', $hex);
             $high_part /= 0x100;
         }
diff --git a/PhpOffice/PhpSpreadsheet/Worksheet/Iterator.php b/PhpOffice/PhpSpreadsheet/Worksheet/Iterator.php
index d8797a3..59aa98d 100644
--- a/PhpOffice/PhpSpreadsheet/Worksheet/Iterator.php
+++ b/PhpOffice/PhpSpreadsheet/Worksheet/Iterator.php
@@ -42,7 +42,7 @@ class Iterator implements \Iterator
     /**
      * Rewind iterator.
      */
-    public function rewind()
+    public function rewind() : void
     {
         $this->position = 0;
     }
@@ -52,7 +52,7 @@ class Iterator implements \Iterator
      *
      * @return Worksheet
      */
-    public function current()
+    public function current() : mixed
     {
         return $this->subject->getSheet($this->position);
     }
@@ -62,7 +62,7 @@ class Iterator implements \Iterator
      *
      * @return int
      */
-    public function key()
+    public function key() : mixed
     {
         return $this->position;
     }
@@ -70,7 +70,7 @@ class Iterator implements \Iterator
     /**
      * Next value.
      */
-    public function next()
+    public function next() : void
     {
         ++$this->position;
     }
@@ -80,7 +80,7 @@ class Iterator implements \Iterator
      *
      * @return bool
      */
-    public function valid()
+    public function valid() : bool
     {
         return $this->position < $this->subject->getSheetCount() && $this->position >= 0;
     }
diff --git a/PhpOffice/PhpSpreadsheet/Worksheet/RowCellIterator.php b/PhpOffice/PhpSpreadsheet/Worksheet/RowCellIterator.php
index 8510d40..ba2a016 100644
--- a/PhpOffice/PhpSpreadsheet/Worksheet/RowCellIterator.php
+++ b/PhpOffice/PhpSpreadsheet/Worksheet/RowCellIterator.php
@@ -113,7 +113,7 @@ class RowCellIterator extends CellIterator
     /**
      * Rewind the iterator to the starting column.
      */
-    public function rewind()
+    public function rewind() : void
     {
         $this->currentColumnIndex = $this->startColumnIndex;
     }
@@ -123,7 +123,7 @@ class RowCellIterator extends CellIterator
      *
      * @return \PhpOffice\PhpSpreadsheet\Cell\Cell
      */
-    public function current()
+    public function current() : mixed
     {
         return $this->worksheet->getCellByColumnAndRow($this->currentColumnIndex, $this->rowIndex);
     }
@@ -133,7 +133,7 @@ class RowCellIterator extends CellIterator
      *
      * @return string
      */
-    public function key()
+    public function key() : mixed
     {
         return Coordinate::stringFromColumnIndex($this->currentColumnIndex);
     }
@@ -141,7 +141,7 @@ class RowCellIterator extends CellIterator
     /**
      * Set the iterator to its next value.
      */
-    public function next()
+    public function next() : void
     {
         do {
             ++$this->currentColumnIndex;
@@ -153,7 +153,7 @@ class RowCellIterator extends CellIterator
      *
      * @throws PhpSpreadsheetException
      */
-    public function prev()
+    public function prev() : void
     {
         do {
             --$this->currentColumnIndex;
@@ -165,7 +165,7 @@ class RowCellIterator extends CellIterator
      *
      * @return bool
      */
-    public function valid()
+    public function valid() : bool
     {
         return $this->currentColumnIndex <= $this->endColumnIndex && $this->currentColumnIndex >= $this->startColumnIndex;
     }
diff --git a/PhpOffice/PhpSpreadsheet/Worksheet/RowIterator.php b/PhpOffice/PhpSpreadsheet/Worksheet/RowIterator.php
index 433cea6..b828306 100644
--- a/PhpOffice/PhpSpreadsheet/Worksheet/RowIterator.php
+++ b/PhpOffice/PhpSpreadsheet/Worksheet/RowIterator.php
@@ -117,7 +117,7 @@ class RowIterator implements \Iterator
     /**
      * Rewind the iterator to the starting row.
      */
-    public function rewind()
+    public function rewind() : void
     {
         $this->position = $this->startRow;
     }
@@ -127,7 +127,7 @@ class RowIterator implements \Iterator
      *
      * @return Row
      */
-    public function current()
+    public function current() : mixed
     {
         return new Row($this->subject, $this->position);
     }
@@ -137,7 +137,7 @@ class RowIterator implements \Iterator
      *
      * @return int
      */
-    public function key()
+    public function key() : mixed
     {
         return $this->position;
     }
@@ -145,7 +145,7 @@ class RowIterator implements \Iterator
     /**
      * Set the iterator to its next value.
      */
-    public function next()
+    public function next() : void
     {
         ++$this->position;
     }
@@ -153,7 +153,7 @@ class RowIterator implements \Iterator
     /**
      * Set the iterator to its previous value.
      */
-    public function prev()
+    public function prev() : void
     {
         --$this->position;
     }
@@ -163,7 +163,7 @@ class RowIterator implements \Iterator
      *
      * @return bool
      */
-    public function valid()
+    public function valid() : bool
     {
         return $this->position <= $this->endRow && $this->position >= $this->startRow;
     }
diff --git a/PhpOffice/PhpSpreadsheet/Writer/Xlsx/StringTable.php b/PhpOffice/PhpSpreadsheet/Writer/Xlsx/StringTable.php
index 19604e4..d86c6b8 100644
--- a/PhpOffice/PhpSpreadsheet/Writer/Xlsx/StringTable.php
+++ b/PhpOffice/PhpSpreadsheet/Writer/Xlsx/StringTable.php
@@ -42,7 +42,7 @@ class StringTable extends WriterPart
             if (!is_object($cellValue) &&
                 ($cellValue !== null) &&
                 $cellValue !== '' &&
-                !isset($aFlippedStringTable[$cellValue]) &&
+                !isset($aFlippedStringTable[\is_float($cellValue) ? (int) $cellValue : $cellValue]) &&
                 ($cell->getDataType() == DataType::TYPE_STRING || $cell->getDataType() == DataType::TYPE_STRING2 || $cell->getDataType() == DataType::TYPE_NULL)) {
                 $aStringTable[] = $cellValue;
                 $aFlippedStringTable[$cellValue] = true;