Learn about Order of Operations Let's cover the order of operations when it comes to expressions. We’re given two problems to solve. The first one wants us to evaluate this following expression by using or applying the correct order of operations. That problem is 4 + 3 x 5. It's an addition operation and a multiplication operation. Before we begin, let's remember what is the order or what are the order of operations. The first is we perform operations that have a parenthesis. Then, we look at operations which has exponents involved. Then we divide or multiply. We do it from left to right. Then we add or subtract and we also do it from left to right. Let's remember that. I'll teach you a quick way to remember this. So in this case, first we look for parenthesis. Well, we don’t have any. Next, we look for exponents. There is nothing there. Is there a division or a multiplication operation? Yup, there is. So we do that first from left to right. So in this case, we leave the addition operation as it is. We multiply first. So 3 x 5 is 15. So we’re done with this. No more division or multiplication, so now we look at addition or subtraction. Well, there is only one addition operation; so let's do that. 4 + 15 becomes 19. So the answer is s19, relatively easy. Now let's look at the second one which is slightly more complicated. The second one says (10 + 15) but this is parenthesis + 20 ÷ 5 x 22. So let's look at this order again. First, we have to do whatever is in the parenthesis. So inside the parenthesis is (10 + 15). So let's do this first. This becomes 25 + 20 ÷ 5 x 22. Now, any more parentheses left? Nope. Well, let's look at exponents. We have one. So let's solve this one first. Two squared or 22 = 4. We copy the rest now. 25 + 20 ÷ 5 x instead of 22 I put 4. No more exponents, so now we move left. Next, divide or multiply and we go from left to right. We’ve got one division and one multiplicati9on. Well, we go from left to right. So 25, we can't act on yet; 20 ÷ 5 is 4 and then multiply it by four. So our division operation is done. So now let's do the multiplication operation. So, 25 is left alone for a minute more, 4 x 4 is 16. Now we've got one operation left which is 25 + 16 which is 41. So, the correct order of operation equals 41. Let's double check our answer; 10 + 15 = 25, that is correct. 20 ÷ 5 = 4, multiply it by 22 = 4. So, 20 ÷ 5 = 4, 4 x 4 = 16, add it to 25, it becomes 41. So, the answer is 41. A key to remember like I told you is first we do parenthesis, then we do exponents, then we do division, then we do multiplication. Division or multiplication is the same. Then, we do addition and then we do subtraction. A key phrase that I've always used to remember this is “Please excuse my dear Aunt Sally; parenthesis, exponents, multiplication, division, addition and subtraction.” This is one way to remember what order to work at.