diff --git a/core/lib/Drupal/Component/Utility/Number.php b/core/lib/Drupal/Component/Utility/Number.php
index 2aadf54123..7cc19b9214 100644
--- a/core/lib/Drupal/Component/Utility/Number.php
+++ b/core/lib/Drupal/Component/Utility/Number.php
@@ -27,7 +27,8 @@ class Number {
    * BCMath (https://secure.php.net/manual/en/book.bc.php).
    *
    * @param $number int|float|string
-   *   The value to normalize.
+   *   The value to normalize. If this is a string, it must be formatted as an
+   *   integer or a float.
    *
    * @return string
    *   The normalized string containing integers with an optional decimal
@@ -48,21 +49,22 @@ public static function normalize($number) {
    * Counts a number's significant decimals.
    *
    * @param int|float|string
-   *   The number as a numeric type or a decimal string.
+   *   The number whose decimals to count. If this is a string, it must be
+   *   formatted as an integer or a float.
    *
    * @return int
    */
-  public static function countSignificantDecimels($number) {
+  public static function countSignificantDecimals($number) {
     $number = static::normalize($number);
 
     // If no decimal separator is encountered, the step is an integer and the
-    // precision is 0 (decimals).
+    // there are 0 significant decimals.
     if (strrpos($number, '.') === FALSE) {
       return 0;
     }
 
-    // If a decimal separator is encountered, the precision is the number of
-    // following digits.
+    // If a decimal separator is encountered, count the number of significant
+    // decimal digits.
     return strlen($number) - strrpos($number, '.') - 1;
   }
 
@@ -82,9 +84,11 @@ public static function countSignificantDecimels($number) {
    * validity.
    *
    * @param int|float|string $value
-   *   The value that needs to be checked.
+   *   The value that needs to be checked. If this is a string, it must be
+   *   formatted as an integer or a float.
    * @param int|float|string $step
-   *   The step scale factor. Must be positive.
+   *   The step scale factor. Must be positive. If this is a string, it must be
+   *   formatted as an integer or a float.
    * @param float $offset
    *   (optional) An offset, to which the difference must be a multiple of the
    *   given step.
@@ -97,18 +101,17 @@ public static function countSignificantDecimels($number) {
   public static function validStep($value, $step, $offset = 0.0) {
     $float_value = (float) abs($value - $offset);
 
-    // Desired precision of comparison is one order of magnitude greater than
-    // the precision of the step.
-    $desired_precision = static::countSignificantDecimels($step) + 1;
+    // The expected number significant decimals is dictated by the step.
+    $expected_significant_decimals = static::countSignificantDecimals($step) + 1;
 
-    // If the value is of higher precision than desired it isn't divisible by
-    // step.
-    $value_precision = static::countSignificantDecimels((string) $float_value);
-    if ($value_precision > $desired_precision) {
+    // If the actual value has more significant decimals than expected, it has a
+    // higher precision than desired it isn't divisible by the step.
+    $actual_significant_decimals = static::countSignificantDecimals((string) $float_value);
+    if ($actual_significant_decimals > $expected_significant_decimals) {
       return FALSE;
     }
 
-    $float_value = (float) round($float_value, $desired_precision);
+    $float_value = (float) round($float_value, $expected_significant_decimals);
 
     // The fractional part of a double has 53 bits. The greatest number that
     // could be represented with that is 2^53. If the given value is even bigger
@@ -120,7 +123,7 @@ public static function validStep($value, $step, $offset = 0.0) {
       return TRUE;
     }
 
-    $expected_float_value = (float) round($step * round($float_value / $step), $desired_precision);
+    $expected_float_value = (float) round($step * round($float_value / $step), $expected_significant_decimals);
     // Now compute that remainder of a division by $step.
     $remainder = (float) abs($float_value - $expected_float_value);
 
diff --git a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
index 4a40fcc75a..eb4658c94b 100644
--- a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
@@ -35,7 +35,7 @@ public function testValidStep($value, $step, $expected) {
   }
 
   /**
-   * @covers ::countSignificantDecimels
+   * @covers ::countSignificantDecimals
    *
    * @dataProvider provideGetPrecision
    *
@@ -45,7 +45,7 @@ public function testValidStep($value, $step, $expected) {
    *   The number to test the precision computation on.
    */
   public function testGetPrecision($expected, $number) {
-    $this->assertEquals($expected, Number::countSignificantDecimels($number));
+    $this->assertEquals($expected, Number::countSignificantDecimals($number));
   }
 
   /**