1 00:00:00,090 --> 00:00:03,030 We just saw the use of arithmetic in code for the first time. 2 00:00:03,030 --> 00:00:06,060 Of course, C sharp can do more than just addition. 3 00:00:06,060 --> 00:00:07,974 You can do anything a basic calculator can do. 4 00:00:07,974 --> 00:00:14,770 There's subtraction, there's multiplication, there's division. 5 00:00:14,770 --> 00:00:17,180 There's also an operator called modulus. 6 00:00:17,180 --> 00:00:21,910 The modulus operator returns the remainder of a division operation. 7 00:00:21,910 --> 00:00:24,776 You can also combine these operations together in a single line. 8 00:00:26,926 --> 00:00:29,750 As you can see, the result of this expression is 6. 9 00:00:29,750 --> 00:00:32,710 When you combine a bunch of operations together like this, 10 00:00:32,710 --> 00:00:36,730 you need to be very careful about what order the operations are performed in. 11 00:00:36,730 --> 00:00:39,610 Some operators have higher precedence than others, and 12 00:00:39,610 --> 00:00:43,070 they are performed first even if they aren't first on the line. 13 00:00:43,070 --> 00:00:47,190 In C sharp this works exactly like the arithmetic you learned in school. 14 00:00:47,190 --> 00:00:51,400 Multiplication, division, and modulus are performed first. 15 00:00:51,400 --> 00:00:56,160 If you have multiple multiplication, division, or modulus operators in a row 16 00:00:56,160 --> 00:00:59,560 like we do here, then they're performed left to right. 17 00:00:59,560 --> 00:01:03,760 Then addition and subtraction are performed, again from left to right. 18 00:01:03,760 --> 00:01:07,680 So in our expression here, we first do 3 times 7. 19 00:01:07,680 --> 00:01:10,960 Then we divide the result of that by 3. 20 00:01:10,960 --> 00:01:14,880 Then we take the modulus of that, that gives us 1. 21 00:01:14,880 --> 00:01:20,240 Then we add 5 and 2 together and subtract 1 and we get 6. 22 00:01:20,240 --> 00:01:23,680 Now what if we wanted the 2- 3 to happen first? 23 00:01:23,680 --> 00:01:27,075 Just like in arithmetic, we can use parentheses for that. 24 00:01:27,075 --> 00:01:29,470 Parentheses have the highest precedence, so 25 00:01:29,470 --> 00:01:32,370 whatever is inside them will get evaluated first. 26 00:01:33,450 --> 00:01:37,859 If we wanted the addition to happen next, we could add more parentheses like this. 27 00:01:38,870 --> 00:01:41,280 The innermost parentheses have the highest precedence, 28 00:01:41,280 --> 00:01:45,460 so what's in them will always get evaluated first. 29 00:01:45,460 --> 00:01:48,500 We don't all encounter long arithmetic like this every day. 30 00:01:48,500 --> 00:01:51,010 Sometimes, I have to stop and think about it. 31 00:01:51,010 --> 00:01:54,350 I'll include the order of operation rules in the teacher's notes for your reference.