added-ModularArithmetic-code (#1217)

* added-ModularArithmetic-code

* fix-typo

* suggested changes

Maths/test/ModularArithmetic.test.js

@@ -0,0 +1,45 @@
+import { ModRing } from '../ModularArithmetic'
+
+describe('Modular Arithmetic', () => {
+  const MOD = 10000007
+  let ring
+  beforeEach(() => {
+    ring = new ModRing(MOD)
+  })
+
+  describe('add', () => {
+    it('Should return 9999993 for 10000000 and 10000000', () => {
+      expect(ring.add(10000000, 10000000)).toBe(9999993)
+    })
+    it('Should return 9999986 for 10000000 and 20000000', () => {
+      expect(ring.add(10000000, 20000000)).toBe(9999986)
+    })
+  })
+
+  describe('subtract', () => {
+    it('Should return 1000000 for 10000000 and 9000000', () => {
+      expect(ring.subtract(10000000, 9000000)).toBe(1000000)
+    })
+    it('Should return 7 for 10000000 and 20000000', () => {
+      expect(ring.subtract(10000000, 20000000)).toBe(7)
+    })
+  })
+
+  describe('multiply', () => {
+    it('Should return 1000000 for 100000 and 10000', () => {
+      expect(ring.multiply(100000, 10000)).toBe(9999307)
+    })
+    it('Should return 7 for 100000 and 10000100', () => {
+      expect(ring.multiply(10000000, 20000000)).toBe(98)
+    })
+  })
+
+  describe('divide', () => {
+    it('Should return 4 for 3 and 11', () => {
+      expect(ring.divide(3, 11)).toBe(4)
+    })
+    it('Should return 2 for 18 and 7', () => {
+      expect(ring.divide(18, 7)).toBe(2)
+    })
+  })
+})