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Original poster

BIDMAS BODMAS

35 replies

MoverOfPaper · 30/10/2020 18:25

Help!

Argument ragging in my house over Y7 maths homework...

Which is correct?

1.Brackets
2.Indices/Order
3.Dividing
4.Multiplication
5.Adding
6.Subtraction

Or

1.Brackets
2.Indices/order
3.Whichever is furthest right of division or multiplication then work from right to left
4.Whichever is furthest right of addition and subtraction and work from right to left?

DD has been taught both ways at various times (she thinks) by different teachers or teaching assistants.

Thank you anyone. I would call NobleGiraffe but hopefully she is up to her neck in gin and not thinking about school.

If you could also provide an example of how to do it I would be so grateful

the question is;

use operations (+ , - , x , /, () to make 12345*6=44 a true statement.

my notes [/ means division but we can't work out how to get that symbol.]

OP posts:
Bobkitten · 30/10/2020 18:55

Wouldn’t the below work - keeps the numbers in order and also avoids double brackets which may be a bit much for some year 7s?
(1x2) + (3x4) + (5x6) = 44

PurpleDaisies · 30/10/2020 18:53

You’re right @WooohVerOfPaper

It doesn’t matter whether you divide then multiply or vice verse, and the same for addition and subtraction. Sometimes deliberated choosing to divide first rather than multiply makes the problem easier to solve rather than just blindly following the “BODMAS” acronym.

TeenPlusTwenties · 30/10/2020 18:51

The second one is 'more' correct as Purple says.

Isola's answer works for the question. You can always put brackets in to be extra clear on meaning (helps in computer science, but obviously not so much in showing BODMAS).

Meredusoleil · 30/10/2020 18:51

5(1+2+3+4)-6

I would say the correct order is as pp said:

  1. Brackets
  2. Indices/Order
  3. Division and Multiplication
  4. Addition and Subtraction
WooohVerOfPaper · 30/10/2020 18:48

Eek. Now I’m confused.

BBC Bitesize mentions the left to right method.

Could you do

Brackets
Indicie
Division
Multiplication
Addition
Subtraction

Or

Brackets
Indicies
Multiplication
Division
Subtraction
Addition

For the same problem and both methods be correct?

PurpleDaisies · 30/10/2020 18:36

There is no mathematical rule about having to go left to right for multiplication/division or addition/subtraction. That is often taught to help students not to miss out parts of their calculation but you get the same results either way. Teaching left to right as a strict rule sometimes reflects a lack of understanding about the orders of operations.

It is more helpful to think of it as
Brackets
Indices
Multiplication and division
Addition and subtraction

woodhill · 30/10/2020 18:33

First one

IsolaPribby · 30/10/2020 18:31

((1+2+3+4)*5)-6

I think that works?

hercatsanddogs · 30/10/2020 18:28

The first one

Original poster
MoverOfPaper · 30/10/2020 18:28

argh...which is furthest LEFT and then working left to right*.

OP posts:
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