diff --git a/ts/numbering/num.ts b/ts/numbering/num.ts
index 5a432732cc..f127817654 100644
--- a/ts/numbering/num.ts
+++ b/ts/numbering/num.ts
@@ -24,6 +24,7 @@ class NumAttributes extends XmlAttributeComponent {
 }
 
 export class Num extends XmlComponent {
+    public id: number;
 
     constructor(numId: number, abstractNumId: number) {
         super("w:num");
@@ -31,5 +32,11 @@ export class Num extends XmlComponent {
             numId: numId,
         }));
         this.root.push(new AbstractNumId(abstractNumId));
+        this.id = numId;
+    }
+
+    public clearVariables(): void {
+        super.clearVariables();
+        delete this.id;
     }
 }
diff --git a/ts/tests/numberingTest.ts b/ts/tests/numberingTest.ts
index 402c6057a0..932b58b5d1 100644
--- a/ts/tests/numberingTest.ts
+++ b/ts/tests/numberingTest.ts
@@ -1,6 +1,7 @@
 import { expect } from "chai";
 import { Numbering } from "../numbering";
 import { AbstractNumbering } from "../numbering/abstract-numbering";
+import { Num } from "../numbering/num";
 import { Formatter } from '../export/formatter';
 
 function jsonify(obj: Object) {
@@ -45,6 +46,36 @@ describe("Numbering", () => {
             })
         });
     });
+
+    describe("#addAbstractNumbering", () => {
+        it("returns a new AbstractNumbering instance", () => {
+            const a2 = numbering.addAbstractNumbering();
+            expect(a2).to.be.instanceof(AbstractNumbering);
+        });
+
+        it("assigns a unique ID to each abstract numbering it creates", () => {
+            const a2 = numbering.addAbstractNumbering();
+            const a3 = numbering.addAbstractNumbering();
+            expect(a2.id).not.to.equal(a3.id);
+        });
+    });
+
+    describe("#addConcreteNumbering", () => {
+        it("returns a new Num instance with its abstract ID set to the AbstractNumbering's ID", () => {
+            const a2 = numbering.addAbstractNumbering();
+            const n = numbering.addConcreteNumbering(a2);
+            expect(n).to.be.instanceof(Num);
+            const tree = new Formatter().format(numbering);
+            expect(n.id).to.equal(a2.id);
+        });
+
+        it("assigns a unique ID to each concrete numbering it creates", () => {
+            const a2 = numbering.addAbstractNumbering();
+            const n = numbering.addConcreteNumbering(a2);
+            const n2 = numbering.addConcreteNumbering(a2);
+            expect(n.id).not.to.equal(n2.id);
+        });
+    });
 });
 
 describe("AbstractNumbering", () => {