diff --git a/mapNumRange.test.js b/mapNumRange.test.js
new file mode 100644
index 000000000..77ca11e8d
--- /dev/null
+++ b/mapNumRange.test.js
@@ -0,0 +1,9 @@
+const expect = require('expect');
+const {mapNumRange} = require('./_30s.js');
+
+test('mapNumRange is a Function', () => {
+  expect(mapNumRange).toBeInstanceOf(Function);
+});
+test('Maps 5 to the range 0-100 from 0-10', () => {
+  expect(distance(5,0,10,0,100)).toEqual(50);
+});