Add Pow.js (#498)

* Add pow.js

* Add tests for Pow.js

Maths/test/Pow.test.js

@@ -0,0 +1,15 @@
+import { pow } from '../Pow'
+
+describe('Pow', () => {
+  it('should return 1 for numbers with exponent 0', () => {
+    expect(pow(2, 0)).toBe(1)
+  })
+
+  it('should return 0 for numbers with base 0', () => {
+    expect(pow(0, 23)).toBe(0)
+  })
+
+  it('should return the base to the exponent power', () => {
+    expect(pow(24, 4)).toBe(331776)
+  })
+})