Added PrimeCheck (#340)

Maths/PrimeCheck.js

@@ -0,0 +1,29 @@
+/*
+  Modified from:
+    https://github.com/TheAlgorithms/Python/blob/master/maths/prime_check.py
+
+  Complexity:
+    O(sqrt(n))
+*/
+
+const PrimeCheck = (n) => {
+  // input: n: int
+  // output: boolean
+  for (let i = 2; i * i <= n; i++) {
+    if (n % i === 0) {
+      return false
+    }
+  }
+  return true
+}
+
+const main = () => {
+  // PrimeCheck(1000003)
+  // > true
+  console.log(PrimeCheck(1000003))
+  // PrimeCheck(1000001)
+  // > false
+  console.log(PrimeCheck(1000001))
+}
+
+main()