diff --git a/lib/evalmath/evalmath.class.php b/lib/evalmath/evalmath.class.php
index 54bba6b3c62..8e3f3818b46 100644
--- a/lib/evalmath/evalmath.class.php
+++ b/lib/evalmath/evalmath.class.php
@@ -210,14 +210,14 @@ class EvalMath {
         $output = array(); // postfix form of expression, to be passed to pfx()
         $expr = trim(strtolower($expr));
         // MDL-14274: new operators for comparison added.
-        $ops   = array('+', '-', '*', '/', '^', '_', '>', '<', '<=', '>=', '==');
-        $ops_r = array('+'=>0,'-'=>0,'*'=>0,'/'=>0,'^'=>1); // right-associative operator?
-        $ops_p = array('+'=>0,'-'=>0,'*'=>1,'/'=>1,'_'=>1,'^'=>2, '>'=>3, '<'=>3, '<='=>3, '>='=>3, '=='=>3); // operator precedence
+        $ops   = array('+', '-', '*', '/', '^', '_', '>', '<', '<=', '>=', '==', '%');
+        $ops_r = array('+'=>0,'-'=>0,'*'=>0,'/'=>0,'^'=>1, '%' => 0); // right-associative operator?
+        $ops_p = array('+'=>0,'-'=>0,'*'=>1,'/'=>1,'_'=>1,'^'=>2, '>'=>3, '<'=>3, '<='=>3, '>='=>3, '=='=>3, '%'=>1); // operator precedence
 
         $expecting_op = false; // we use this in syntax-checking the expression
                                // and determining when a - is a negation
 
-        if (preg_match("/[^\w\s+*^\/()\.,-<>=]/", $expr, $matches)) { // make sure the characters are all good
+        if (preg_match("/[^\%\w\s+*^\/()\.,-<>=]/", $expr, $matches)) { // make sure the characters are all good
             return $this->trigger(get_string('illegalcharactergeneral', 'mathslib', $matches[0]));
         }
 
@@ -433,7 +433,7 @@ class EvalMath {
                     $stack->push($this->pfx($this->f[$fnn]['func'], $args)); // yay... recursion!!!!
                 }
             // if the token is a binary operator, pop two values off the stack, do the operation, and push the result back on
-            } elseif (in_array($token, array('+', '-', '*', '/', '^', '>', '<', '==', '<=', '>='), true)) {
+            } elseif (in_array($token, array('+', '-', '*', '/', '^', '>', '<', '==', '<=', '>=', '%'), true)) {
                 if (is_null($op2 = $stack->pop())) return $this->trigger(get_string('internalerror', 'mathslib'));
                 if (is_null($op1 = $stack->pop())) return $this->trigger(get_string('internalerror', 'mathslib'));
                 switch ($token) {
@@ -458,6 +458,8 @@ class EvalMath {
                         $stack->push((int)($op1 <= $op2)); break;
                     case '>=':
                         $stack->push((int)($op1 >= $op2)); break;
+                    case '%':
+                        $stack->push($op1%$op2); break;
                 }
             // if the token is a unary operator, pop one value off the stack, do the operation, and push it back on
             } elseif ($token == "_") {
diff --git a/lib/evalmath/readme_moodle.txt b/lib/evalmath/readme_moodle.txt
index 3d460eb9986..948c9c39a20 100644
--- a/lib/evalmath/readme_moodle.txt
+++ b/lib/evalmath/readme_moodle.txt
@@ -32,4 +32,21 @@ e.g. if (and(condition_1, condition_2, ... condition_n))
 
 Changes by Raquel Ortega (MDL-76413)
 * Avoid PHP 8.2: Partially-supported callable deprecations
-* eg: call_user_func_array(array('self', 'sum'), $args to call_user_func_array(array(self::class, 'sum'), $args)
\ No newline at end of file
+* eg: call_user_func_array(array('self', 'sum'), $args to call_user_func_array(array(self::class, 'sum'), $args)
+
+Changes by Meirza (MDL-75464)
+* EvalMath has unit tests in lib/tests/mathslib_test.php,
+  since version 1.0.1, there are two additional tests:
+  - shouldSupportModuloOperator()
+  - shouldConsiderDoubleMinusAsPlus()
+  To pass the test, some modifications must be made:
+  - Adjust the test code so it can run properly by using \calc_formula.
+  Please see the differences between the code in MDL-75464 and the upstream code.
+  - In the dataprovider for both tests, add the formula in the first array with "=" at the first character.
+  Before:
+  ```
+  'a%b', // 9%3 => 0
+  ```
+  After:
+  ```
+  '=a%b', // 9%3 => 0
\ No newline at end of file
diff --git a/lib/tests/mathslib_test.php b/lib/tests/mathslib_test.php
index 8e8368add18..5994e2fffdf 100644
--- a/lib/tests/mathslib_test.php
+++ b/lib/tests/mathslib_test.php
@@ -317,4 +317,93 @@ class mathslib_test extends \basic_testcase {
         $result = $formula->evaluate();
         $this->assertTrue(is_float($result));
     }
+
+    /**
+     * Tests the modulo operator.
+     *
+     * @covers calc_formula::evaluate
+     * @dataProvider moduloOperatorData
+     *
+     * @param string $formula
+     * @param array $values
+     * @param int|float $expectedResult
+     */
+    public function shouldSupportModuloOperator($formula, $values, $expectedResult)
+    {
+        $formula = new calc_formula($formula);
+        $formula->set_params($values);
+        $this->assertEquals($expectedResult, $formula->evaluate());
+    }
+
+    /**
+     * Data provider for shouldSupportModuloOperator
+     *
+     * @return array
+     */
+    public function moduloOperatorData() {
+        return array(
+            array(
+                '=a%b', // 9%3 => 0
+                array('a' => 9, 'b' => 3),
+                0
+            ),
+            array(
+                '=a%b', // 10%3 => 1
+                array('a' => 10, 'b' => 3),
+                1
+            ),
+            array(
+                '=10-a%(b+c*d)', // 10-10%(7-2*2) => 9
+                array('a' => '10', 'b' => 7, 'c' => -2, 'd' => 2),
+                9
+            )
+        );
+    }
+
+    /**
+     * Tests the double minus as plus.
+     *
+     * @covers calc_formula::evaluate
+     * @dataProvider doubleMinusData
+     *
+     * @param string $formula
+     * @param array $values
+     * @param int|float $expectedResult
+     */
+    public function shouldConsiderDoubleMinusAsPlus($formula, $values, $expectedResult)
+    {
+        $formula = new calc_formula($formula);
+        $formula->set_params($values);
+        $this->assertEquals($expectedResult, $formula->evaluate());
+    }
+
+    /**
+     * Data provider for shouldConsiderDoubleMinusAsPlus
+     *
+     * @return array
+     */
+    public function doubleMinusData() {
+        return array(
+            array(
+                '=a+b*c--d', // 1+2*3--4 => 1+6+4 => 11
+                array(
+                    'a' => 1,
+                    'b' => 2,
+                    'c' => 3,
+                    'd' => 4
+                ),
+                11
+            ),
+            array(
+                '=a+b*c--d', // 1+2*3---4 => 1+6-4 => 3
+                array(
+                    'a' => 1,
+                    'b' => 2,
+                    'c' => 3,
+                    'd' => -4
+                ),
+                3
+            )
+        );
+    }
 }
diff --git a/lib/thirdpartylibs.xml b/lib/thirdpartylibs.xml
index c6aca5f4757..6191e21b044 100644
--- a/lib/thirdpartylibs.xml
+++ b/lib/thirdpartylibs.xml
@@ -42,7 +42,7 @@
     <location>evalmath</location>
     <name>EvalMath</name>
     <description>Class to safely evaluate math expressions.</description>
-    <version>1.0.0</version>
+    <version>1.0.1</version>
     <license>BSD</license>
     <repository>https://github.com/dbojdo/eval-math</repository>
     <copyrights>