Question

“Simplify the expression: 310 – 20 ÷ 2 × 5 + 13”



Below is a student answer:

310 – 20 ÷ 2 × 5 + 13

310 – 20 ÷ 10 + 13

310 – 2 + 13

310 – 15

295



Part A) The student made two mistakes. EXPLAIN what those two

mistakes were in regards to the order of operations.





Part B) Simplify the expression yourself using the order of

operations.

Answer 1

Do you know about order of operations, and PEMDAS?

Answer 2

No

Answer 3

Should they have started from the back first?

Answer 4

Or the front?

Answer 5

PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.
It's an order in which you're supposed to solve math problems, like this.
Also, M & D, and A & S can be switched up if one of them shows up first in the problem.

Answer 6

In the original problem, you have 20/2*5, which is where the first mistake is.
The student did the 2*5 part first, to get 20/10.
You cannot do this, according to order of operations. You must do the 20/2 division first, because it comes up first in the problem.

Answer 7

Instead of 310 – 20 ÷ 10 + 13,
It should be 310 - 10 * 5 + 13

Answer 8

Thank you

Answer 9

The second problem comes during the addition and subtraction part. You have to do it in order as it shows up in the problem. The student did the addition on the right side first, but you have to go from left to right.

Answer 10

So when i Simplify the expression it should be:
310 – 20 ÷ 2 × 5 + 13”
310 - 20 / 10 plus 13

Answer 11

Noooo, that was the problem we found.
You would have to do 20/2 first, because it comes up first.

Answer 12

oh so you do the one right next to the first number?

Answer 13

Yeah, after you do the 20/2, you'll multiply that answer by 5. Since divison and multiplication operations come before addition and subtraction, I showed you in PEMDAS.

Answer 14

i get it now, you want me to try again?

Answer 15

Yeah, lemme see if you can evaluate the problem correctly, which is what you're supposed to do for Part B.

Answer 16

310 – 20 ÷ 2 × 5 + 13
310 - 10 * 5 plus 13
310 - 50 plus 13
310 - 50
lol it got hard

Answer 17

opps

Answer 18

310 - 63

Answer 19

Noooo, you can't do that either. That was the problem the student made.
You have to go from left to right. So you have to do 310 - 50 first.

Answer 20

can u copy the right part of it and paste it

Answer 21

310 - 50 + 13
The last part of PEMDAS is Addition and Subtraction. But you still have to do it in order of the problem.
310 - 50 = 260
260 + 13 = 273

Answer 22

i quittt sorry

Answer 23

310 – 20 ÷ 2 × 5 + 13
310 - 10 * 5 plus 13
310 - 50 = 260
260 + 13 = 273 ???

Answer 24

or
310 – 20 ÷ 2 × 5 + 13
20 / 2 = 10
10 * 5 = 50
310 - 50 = 260
260 + 13 = 273

Answer 25

@iPwnBunnies

Answer 26

They're both right. I was just breaking it up so you can see each individual section I was doing.

Answer 27

Thank You

Answer 28

what one should i put for the test