Missing Operations

Each red box represents a missing operation (plus, minus, times or divide).
Can you work out what they are?

(38  31)  30 = 1148

24  (24  39) = 9

(29  32)  29 = 957

(27  35)  (21  32) = 3


Topics: Starter | Arithmetic

  • Dave Loboda, St John's Middle School, Bromsgrove
  • Have used a number of your starters and found them to be very useful and enjoyable. We used the problem for 9 December today and one of the pupils pointed out what he felt was an error in the solution.

    You gave 24 + (39 + 36) x 36 = 3564 it was pointed out that, using BIDMAS strictly, you should complete the brackets first, then multiply by 36 before adding the 24 at the start which will give 2724

    Thank you
  • Transum,
  • Thanks Dave. It is very good of you to take time to point out the error. The numbers and operations in this starter are generated randomly each time the page is refreshed. The combination of randomly generated operations you came across was handled incorrectly by the software. The problem has now hopefully been solved.
  • Franziska Fisken, Telford
  • I used this activity and found it a useful intro to BIDMAS /BODMAS!
  • Liz Richards, Lambeth College
  • When will Maths teachers realise that bidmas/bodmas does not always work?
  • Nairn Spink, High School Of Dundee
  • Hello transum,the class enjoyed this starter.we will definetly come back and do more activities. We were very happy when we got the answers.
  • Mary Tonti, Cleveland, OH
  • This is the second time to your site. I am getting ready to go back to school soon and althought we are not in school right now, I can see how this would get the kids to experiment with the different operations.
  • Paul Harris, Chalfont St Peter
  • Liz, coming at this from a Mathematician AND a maths teacher, what do you mean?
    BIDMAS/BODMAS is not some phrase that Maths teachers have invented to try and answer questions in Maths, it is the order of operations which happens, dictated by the constructs on which Mathematics is built. Brackets are computed first, then powers, then Multiplication/Division, computed in order of encounter from left to right, and finally Addition/Subtraction from left to right. I am always open to being wrong but as far as I know, BIDMAS is always going to hold as it is principle which underpins computation. Can you provide a counter example?
  • M Shepherd, The St Lawrence Academy
  • When will people realise that BODMAS / BIDMAS doesn't work?
    (comment from previous post)
    Yes it does, but you don't write it as six consecutive letters, you write B then O then D on top of M and then A on top of S.
    This reminds classes that divide & multiply and add & subtract happen simultaneously, and should therefore be done in the order they appear.
    This avoids the confusion of 10 - 3 + 2 equaling 5 instead of 9, for example.
    Anyone still teaching BODMAS as a six letter word should think on this...
  • Vikram,
  • This really helped me in my learning!!!

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Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click the button above to regenerate another version of this starter from random numbers.

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Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.


Here is the URL which will take them to a related student activity.


Student Activity

BIDMAS is an acronym reminding students of the order of operation used when evaluating expressions involving a number of different operations. The letters of BIDMAS stand for:

When only addition and subtraction (or only multiplication and division) are left in an expression work them out in the order you find them, starting from the left and working towards the right.


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