diff --git a/core/lib/Drupal/Component/Utility/Number.php b/core/lib/Drupal/Component/Utility/Number.php
index 39143d9..7038017 100644
--- a/core/lib/Drupal/Component/Utility/Number.php
+++ b/core/lib/Drupal/Component/Utility/Number.php
@@ -17,9 +17,18 @@ class Number {
    *
    * This is based on the number/range verification methods of webkit.
    *
-   * @param float $value
+   * This is called by Drupal\Core\Render\Element\Number::validateNumber() to
+   * validate a numeric field. That function passes the $value parameter as a
+   * string, as provided on the text field of the form. Besides integers and
+   * floating numbers, we also support decimal numbers which are not stored in
+   * IEEE 754 format. In somewhat higher precisions for these numbers, the $step
+   * value cannot accurately represent the desired precision, when it is passed
+   * as a float. Passing it as a string bypasses this loss of precision and
+   * enables a correct calculation of the step validity.
+   *
+   * @param float|string $value
    *   The value that needs to be checked.
-   * @param float $step
+   * @param float|string $step
    *   The step scale factor. Must be positive.
    * @param float $offset
    *   (optional) An offset, to which the difference must be a multiple of the
diff --git a/core/modules/field/src/Tests/Number/NumberFieldTest.php b/core/modules/field/src/Tests/Number/NumberFieldTest.php
index 09463d7..cd757b2 100644
--- a/core/modules/field/src/Tests/Number/NumberFieldTest.php
+++ b/core/modules/field/src/Tests/Number/NumberFieldTest.php
@@ -41,14 +41,14 @@ protected function setUp() {
   function testNumberDecimalField() {
     // Create a field with settings to validate.
     $field_name = Unicode::strtolower($this->randomMachineName());
-    FieldStorageConfig::create(array(
+    FieldStorageConfig::create([
       'field_name' => $field_name,
       'entity_type' => 'entity_test',
       'type' => 'decimal',
-      'settings' => array(
+      'settings' => [
         'precision' => 10, 'scale' => 4,
-      )
-    ))->save();
+      ],
+    ])->save();
     FieldConfig::create([
       'field_name' => $field_name,
       'entity_type' => 'entity_test',
@@ -74,24 +74,26 @@ function testNumberDecimalField() {
     $this->assertFieldByName("{$field_name}[0][value]", '', 'Widget is displayed');
     $this->assertRaw('placeholder="0.00"');
 
-    // Submit a signed decimal value within the allowed precision and scale.
-    $valid_entries = array(
+    // Submit a few signed decimal value within the allowed precision and scale.
+    $valid_entries = [
       '-1234.5678',
       '19999.0000',
       '99999.0000',
-    );
+      '9990009888.96',
+      '990088999.0099',
+    ];
 
     foreach ($valid_entries as $valid_entry) {
       $this->drupalGet('entity_test/add');
-      $edit = array(
+      $edit = [
         "{$field_name}[0][value]" => $valid_entry,
-      );
+      ];
       $this->drupalPostForm(NULL, $edit, t('Save'));
       preg_match('|entity_test/manage/(\d+)|', $this->url, $match);
       $id = $match[1];
-      $this->assertText(t('entity_test @id has been created.', array('@id' => $id)), 'Entity was created');
-      $this->assertRaw($valid_entry, 'Value is displayed.');
-      $this->assertNoRaw(t('%name is not a valid number.', array('%name' => $field_name)), 'Values are accepted');
+      $this->assertText(t('entity_test @id has been created.', ['@id' => $id]), 'Entity was created');
+      $this->assertRaw($valid_entry, t('Value @val is displayed.', ['@val' => $valid_entry]));
+      $this->assertNoRaw(t('%name is not a valid number.', ['%name' => $field_name]), 'Values are accepted');
     }
 
     // Try to create entries with more than one decimal separator; assert fail.
diff --git a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
index 3e32629..a4414bb 100644
--- a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
@@ -89,6 +89,11 @@ public static function providerTestValidStep() {
       // Step mismatches very close to being valid.
       array(70 + 9e-7, 10 + 9e-7, FALSE),
       array(1936.5, 3e-8, FALSE),
+
+      // These floats are valid, but might trigger FP math idiosyncracies.
+      // @see https://www.drupal.org/node/2230909
+      [9990009888.96, 0.01, TRUE],
+      [990088999.0099, 0.0001, TRUE],
     );
   }