1 00:00:00,000 --> 00:00:02,640 Now the goal of this exercise is 2 00:00:02,640 --> 00:00:06,000 to write a program using what you've learned about if 3 00:00:06,000 --> 00:00:09,330 and else conditional statements to figure out 4 00:00:09,330 --> 00:00:14,330 whether if an input number is odd or even. 5 00:00:14,430 --> 00:00:17,670 So what differentiates odd and even numbers? 6 00:00:17,670 --> 00:00:21,720 Well, even numbers, by definition, can be divided 7 00:00:21,720 --> 00:00:24,870 by two with no remainder. 8 00:00:24,870 --> 00:00:29,340 That means that the final result has no decimal places. 9 00:00:29,340 --> 00:00:33,360 It's a whole number and the division is clean. 10 00:00:33,360 --> 00:00:35,610 Whereas if you took an odd number, 11 00:00:35,610 --> 00:00:38,460 like three, and divided it by two, 12 00:00:38,460 --> 00:00:41,820 the result is 1.5, and it does have a decimal place. 13 00:00:41,820 --> 00:00:44,040 It's not a whole number. 14 00:00:44,040 --> 00:00:48,090 In Python and in many other programming languages, 15 00:00:48,090 --> 00:00:49,830 there's a way to check 16 00:00:49,830 --> 00:00:53,220 if a division occurs with no remainder, 17 00:00:53,220 --> 00:00:56,310 and that is through something called the modulo. 18 00:00:56,310 --> 00:01:00,630 Now, you can use the modulo by writing a percentage sign % 19 00:01:00,630 --> 00:01:04,379 and that will give you the remainder after a division. 20 00:01:04,379 --> 00:01:09,380 For example, if you divide six by two, that equals three 21 00:01:09,750 --> 00:01:11,580 with no remainder. 22 00:01:11,580 --> 00:01:16,383 So if 6 % 2, the result would be 0. 23 00:01:17,670 --> 00:01:22,620 But if you try to divide five by two, then two can go 24 00:01:22,620 --> 00:01:27,620 into five two times, but there is one remainder. 25 00:01:28,260 --> 00:01:32,010 So five modulo two is equal to one (5 % 2 = 1). 26 00:01:32,010 --> 00:01:34,410 You can take a look in the description pane to 27 00:01:34,410 --> 00:01:39,410 see this written out and understand how the modulo works 28 00:01:40,380 --> 00:01:43,470 and you can get more details on the modulo by Googling 29 00:01:43,470 --> 00:01:44,313 for it as well. 30 00:01:45,180 --> 00:01:50,180 In our case, we want our code to be able to check the input 31 00:01:50,880 --> 00:01:54,300 number and it's ready coming in, and we're converting it 32 00:01:54,300 --> 00:01:55,980 into a whole number. 33 00:01:55,980 --> 00:01:59,280 And we're going to check to see if it's odd, or even. 34 00:01:59,280 --> 00:02:02,760 If it's odd, we're going to print into the output, 35 00:02:02,760 --> 00:02:05,250 "This is an odd number." 36 00:02:05,250 --> 00:02:06,750 And if it's even, we're going to print, 37 00:02:06,750 --> 00:02:09,539 "This is an even number." 38 00:02:09,539 --> 00:02:12,690 That is the task at hand, and now it's for you 39 00:02:12,690 --> 00:02:15,900 to start struggling and trying to figure out 40 00:02:15,900 --> 00:02:18,663 how to solve this code exercise. 41 00:02:22,860 --> 00:02:24,900 The first thing we're going to check using an 42 00:02:24,900 --> 00:02:28,410 if statement is if the value that's stored 43 00:02:28,410 --> 00:02:33,410 in our variable number is divisible by two 44 00:02:33,450 --> 00:02:37,590 and has no remainder, and we're going to do this using 45 00:02:37,590 --> 00:02:41,670 the modulo, so number % 2, and then we 46 00:02:41,670 --> 00:02:46,670 use the double equal (==) sign to check to see if it equals 0. 47 00:02:47,040 --> 00:02:52,020 And this is equivalent to saying if number divided 48 00:02:52,020 --> 00:02:56,190 by 2 has no decimal places, well then in that case 49 00:02:56,190 --> 00:02:58,470 it must be an even number. 50 00:02:58,470 --> 00:03:01,500 So that's why on the next line, Line 6, 51 00:03:01,500 --> 00:03:04,560 we have an indented print statement. 52 00:03:04,560 --> 00:03:08,460 This print statement is going to be carried 53 00:03:08,460 --> 00:03:13,460 out if the Line 5 condition is true. 54 00:03:15,270 --> 00:03:18,960 If the input was indeed an even number, 55 00:03:18,960 --> 00:03:23,760 say it was Number 4, 4/ 2, 56 00:03:23,760 --> 00:03:27,300 2 goes into 4 twice, and there is no remainder. 57 00:03:27,300 --> 00:03:28,133 So therefore 58 00:03:28,133 --> 00:03:31,830 the modulo operator gives us a result of 0. 59 00:03:31,830 --> 00:03:34,230 So if that condition is true, it's going to fall 60 00:03:34,230 --> 00:03:37,680 into the indented print statement and printout, 61 00:03:37,680 --> 00:03:39,873 "This is an even number." 62 00:03:40,800 --> 00:03:44,850 Alternatively, or in this case, in the else condition, 63 00:03:44,850 --> 00:03:49,850 so if Line 5 condition was false, it did not work 64 00:03:51,180 --> 00:03:54,180 and there was a remainder, then we're going to print out, 65 00:03:54,180 --> 00:03:56,583 "This is an odd number." 66 00:03:57,660 --> 00:04:00,930 This is a way that we can manipulate numbers 67 00:04:00,930 --> 00:04:03,330 and check them and use what we learned 68 00:04:03,330 --> 00:04:06,750 about conditionals to check if a condition is true 69 00:04:06,750 --> 00:04:10,890 and behave in a certain way, or if that condition was false, 70 00:04:10,890 --> 00:04:14,220 then our program should behave in a different way. 71 00:04:14,220 --> 00:04:16,110 If you need to make any changes to your code 72 00:04:16,110 --> 00:04:17,010 feel free to go back 73 00:04:17,010 --> 00:04:20,130 to the previous slide and make those changes. 74 00:04:20,130 --> 00:04:21,660 Don't feel like you've failed 75 00:04:21,660 --> 00:04:22,860 or you're cheating or whatever. 76 00:04:22,860 --> 00:04:25,620 This is all a part of the learning process. 77 00:04:25,620 --> 00:04:26,610 It's okay to look 78 00:04:26,610 --> 00:04:29,550 at the solution and learn from the solution too. 79 00:04:29,550 --> 00:04:32,300 You don't have to figure everything out the first time.