diff --git a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
index eb4658c94b..f951a339a1 100644
--- a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
@@ -67,15 +67,25 @@ public function provideGetPrecision() {
       [1, '0.0'],
       [0, -0.0],
       [1, '-0.0'],
-      # The maximum supported precision is 15 decimals.
+      # The maximum supported float precision is 15 decimals.
       [0, 0.0000000000000],
-      [15, '0.000000000000000'],
       [0, -0.0000000000000],
-      [15, '-0.000000000000000'],
       [9, -0.0000000090000],
-      [15, '-0.000000009000000'],
       [9, -0.0000000090000],
+      [9, -0.00000000900000],
+      [9, -0.000000009000000000],
+      [15, -0.0000000090000009],
+      [15, -0.00000000900000099],
+      [15, -0.000000009000000900009],
+      # Numeric strings do not suffer from the system-specific limitations to
+      # float precision, so they can contain many more significant decimals.
+      # This is especially useful when working with solutions such as BCMath
+      # (https://secure.php.net/manual/en/book.bc.php)
+      [15, '0.000000000000000'],
+      [15, '-0.000000000000000'],
       [15, '-0.000000009000000'],
+      [16, '-0.0000000090000000'],
+      [20, '-0.00000000900000000000'],
     ];
   }