Added basic algorithm for testing in number is prime resolve manrajgr…

…over#10

src/algorithms/math/index.js

@@ -1,12 +1,14 @@
 const extendedEuclidean = require('./extended_euclidean');
 const gcd = require('./gcd');
+const isprime = require('./is_prime');
 const fastexp = require('./fast_exp');
 const lcm = require('./lcm');
 const modularInverse = require('./modular_inverse');
 
 module.exports = {
   extendedEuclidean,
   gcd,
+  isprime,
   fastexp,
   lcm,
   modularInverse

src/algorithms/math/is_prime.js

@@ -0,0 +1,16 @@
+/**
+ * Checks in given number is prime
+ * @param  {Number} n Number
+ * @return {Boolean} Returns true for prime number, for other false
+ */
+function isprime(n) {
+  if (n < 2) return false;
+  for (let i = 2; i < n; i += 1) {
+    if (n % i === 0) {
+      return false;
+    }
+  }
+  return n > 1;
+}
+
+module.exports = isprime;

test/algorithms/math/testIsPrime.js

@@ -0,0 +1,37 @@
+/* eslint-env mocha */
+const isprime = require('../../../src').algorithms.math.isprime;
+
+const assert = require('assert');
+
+describe('PrimeTest', () => {
+  it('should return false for negative', () => {
+    assert.equal(isprime(-1), false);
+  });
+
+  it('should return false for 0', () => {
+    assert.equal(isprime(-1), false);
+  });
+  it('should return false for 2', () => {
+    assert.equal(isprime(1), false);
+  });
+
+  it('should return true for 2', () => {
+    assert.equal(isprime(2), true);
+  });
+
+  it('should return true for 3', () => {
+    assert.equal(isprime(3), true);
+  });
+
+  it('should return true for 31', () => {
+    assert.equal(isprime(31), true);
+  });
+
+  it('should return true for 97', () => {
+    assert.equal(isprime(97), true);
+  });
+
+  it('should return true for 7919', () => {
+    assert.equal(isprime(7919), true);
+  });
+});