diff --git a/src/lib/esnext.d.ts b/src/lib/esnext.d.ts
index 10d459816a349..a0d74d676f7ad 100644
--- a/src/lib/esnext.d.ts
+++ b/src/lib/esnext.d.ts
@@ -1,11 +1,12 @@
-/// <reference lib="es2025" />
-/// <reference lib="esnext.intl" />
-/// <reference lib="esnext.collection" />
-/// <reference lib="esnext.decorators" />
-/// <reference lib="esnext.disposable" />
-/// <reference lib="esnext.array" />
-/// <reference lib="esnext.error" />
-/// <reference lib="esnext.sharedmemory" />
-/// <reference lib="esnext.typedarrays" />
-/// <reference lib="esnext.temporal" />
-/// <reference lib="esnext.date" />
+/// <reference lib="es2025" />
+/// <reference lib="esnext.intl" />
+/// <reference lib="esnext.collection" />
+/// <reference lib="esnext.decorators" />
+/// <reference lib="esnext.disposable" />
+/// <reference lib="esnext.array" />
+/// <reference lib="esnext.error" />
+/// <reference lib="esnext.math" />
+/// <reference lib="esnext.sharedmemory" />
+/// <reference lib="esnext.typedarrays" />
+/// <reference lib="esnext.temporal" />
+/// <reference lib="esnext.date" />
\ No newline at end of file
diff --git a/src/lib/esnext.math.d.ts b/src/lib/esnext.math.d.ts
new file mode 100644
index 0000000000000..7de13642e009e
--- /dev/null
+++ b/src/lib/esnext.math.d.ts
@@ -0,0 +1,15 @@
+/** TypeScript Definition File
+ * Created: ES2026
+ */
+
+interface Math {
+    /**
+     * Returns the sum of the values in the iterable using a more precise
+     * summation algorithm than naive floating-point addition.
+     * Returns `-0` if the iterable is empty.
+     * @param numbers An iterable (such as an Array) of numbers.
+     * @throws {TypeError} If `numbers` is not iterable, or if any value in the iterable is not of type `number`.
+     * @throws {RangeError} If the iterable yields 2^53 or more values.
+     */
+    sumPrecise(numbers: Iterable<number>): number;
+}