ruby_is_prime.ipynb

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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Write some code in either Ruby or JavaScript that will determine if a given number is prime."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Prime number is a whole number that has factor of 1 and itself. Like 11 = 1 x 11, meaning its factor is 1 and 11 itself.\n",
    "\n",
    "Prime number starts from 2,3,5,7,11, etc.\n",
    "Prime number cannot be product of any 2 numbers smaller than iteself, such as 2 x 3 = 6\n",
    "\n",
    "I can also think that N modulus 2 until it's square root number, cannot be 0. So we can have loop until sqrt(N)\n"
   ]
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       ":is_prime"
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   "source": [
    "def is_prime(n)\n",
    "  if n<2\n",
    "    return false\n",
    "  else\n",
    "    for i in 2..Math.sqrt(n)\n",
    "      if (n%i ==0)\n",
    "        return false\n",
    "      end\n",
    "    end\n",
    "    return true\n",
    "  end\n",
    "end"
   ]
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   "cell_type": "code",
   "execution_count": 25,
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     "data": {
      "text/plain": [
       "true"
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     "execution_count": 25,
     "metadata": {},
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   "source": [
    "is_prime 41"
   ]
  },
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   "cell_type": "code",
   "execution_count": 26,
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      "text/plain": [
       "false"
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     "execution_count": 26,
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   "source": [
    "is_prime 57"
   ]
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   "cell_type": "code",
   "execution_count": 27,
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     "data": {
      "text/plain": [
       "true"
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     "execution_count": 27,
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   "source": [
    "is_prime 53"
   ]
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   "cell_type": "markdown",
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   "source": [
    "However in Ruby, we can do something like x.prime? by `require 'prime'`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
      ]
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     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "require 'prime'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
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     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "53.prime?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "false"
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "57.prime?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {
    "collapsed": false
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "true"
      ]
     },
     "execution_count": 31,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "41.prime?"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
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